SECURITIES AND EXCHANGE COMMISSION

                             Washington, D.C. 20549

                   -------------------------------------------


                                    FORM 8-K

                                 CURRENT REPORT



                       Pursuant to Section 13 or 15(d) of
                       the Securities Exchange Act of 1934



                                 Date of Report
                             (Date of earliest event
                                   reported):

                                  June 12, 1998

                    ----------------------------------------


                               THERMO SENTRON INC.
             (Exact name of Registrant as specified in its charter)


Delaware                        1-14254                      41-1827303
(State or other               (Commission                   (I.R.S. Employer
jurisdiction of               File Number)                Identification Number)
incorporation or
organization)


501 90th Avenue N.W.
Minneapolis, Minnesota                                              55433
(Address of principal executive offices)                          (Zip Code)


                                 (781) 622-1000
                         (Registrant's telephone number
                              including area code)



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Item 2.  Acquisition or Disposition of Assets

        On June 12, 1998, Thermo Sentron Inc. (the "Company") acquired the three
businesses  that  constitute  the  Graseby  product-monitoring  group  ("Graseby
Product  Monitoring")  from  Graseby  Limited  (the  "Seller").  The  businesses
acquired   design,   manufacture  and  distribute   specialized   packaged-goods
equipment,  including  checkweighers  and metal detectors,  primarily for use by
food producers and  pharmaceutical  companies.  Graseby  Product  Monitoring had
revenues of approximately $46 million for the year ended December 31, 1997.

         The  acquisition was made pursuant to an Agreement dated March 13, 1998
(as  amended,  the  "Agreement"),  between  the  Seller,  the Company and Thermo
Environmental  Instruments  Inc.,  which  acquired  a separate  business  of the
Seller.  Smiths  Industries  plc, the parent  company of the Seller,  and Thermo
Electron  Corporation,  the indirect parent company of the Company and of Thermo
Environmental  Instruments  Inc.,  guaranteed the respective  obligations of the
parties.

         The purchase price of Graseby Product  Monitoring was approximately $43
million,  net of cash acquired.  The purchase price is subject to a post-closing
adjustment equal to the amount by which the net operating assets (excluding cash
balances and certain other identified items) of Graseby Product Monitoring as of
the closing date are greater or less than,  as the case may be,  certain  target
amounts set forth in the Agreement.

         The consideration  paid for Graseby Product Monitoring was based on the
Company's determination of the fair market value of Graseby Product Monitoring's
business,  and  the  terms  of the  Agreement  were  determined  by  arms-length
negotiation among the parties.

         To finance the acquisition,  the Company utilized  approximately  $34.6
million of available  cash and  approximately  $8.6 million of  borrowings  from
Thermo  Electron.  The  indebtedness to Thermo Electron bears interest at a rate
equal to the 90-day Commercial Paper Composite Rate plus 25 basis points, set at
the beginning of each quarter, and is due December 15, 1998.

         The  Company  has no  present  intention  to use the  assets of Graseby
Product Monitoring for purposes materially different from the purposes for which
such assets were used prior to the acquisition. However, the Company will review
such  business's  assets,  corporate  structure,   capitalization,   operations,
properties,  policies,  managements  and personnel and, upon  completion of this
review,  may develop  additional or  alternative  plans or proposals,  including
mergers,   transfers  of  a  material  amount  of  assets  or  other  additional
transactions or changes relating to such business.

     Item 7.  Financial  Statements,  Pro  Forma  Combined  Condensed  Financial
Information and Exhibits

             (a)         Financial Statements of Business Acquired:  Information
                         meeting  the  requirements  of this  Item  7(a) will be
                         filed by amendment  within the time period permitted by
                         Item 7(a)(4) of Form 8-K.

             (b)         Pro Forma  Combined  Condensed  Financial  Information:
                         Information  meeting the requirements of this Item 7(b)
                         will be  filed by  amendment  within  the  time  period
                         permitted by Item 7(a)(4) of Form 8-K.

             (c)          Exhibits

                           2.1*     Agreement  dated March 13, 1998 for the sale
                                    and  purchase  of all of  the  issued  share
                                    capitals of Graseby Allen  Limited,  Graseby
                                    Product  Monitoring  Limited,   Goring  Kerr
                                    Detection Limited, Graseby Goring Kerr Inc.,
                                    Graseby  Andersen Inc. and part of the share
                                    capital  of  Allen  France   S.A.,   between
                                    Graseby   Limited,    Thermo   Environmental
                                    Instruments   Inc.,   Thermo  Sentron  Inc.,
                                    Smiths  Industries  plc and Thermo  Electron
                                    Corporation.  Pursuant to Item  601(b)(2) of
                                    regulation  S-K,  schedules  and exhibits to
                                    this  Agreement   have  been  omitted.   The
                                    Company   hereby   undertakes   to   furnish
                                    supplementally  a copy of such schedules and
                                    exhibits to the Commission upon request.

                           2.2     Amendment  Agreement dated May 7, 1998  
                                   between Graseby Limited,  Thermo 
                                   Environmental Instruments  Inc., Thermo
                                   Sentron Inc., Smiths Industries plc and 
                                   Thermo Electron Corporation.

                           2.3      Agreement,  dated June 9,  1998,  to further
                                    amend the sale and purchase  agreement dated
                                    March  13,  1998  between  Graseby  Limited,
                                    Thermo   Environmental   Instruments   Inc.,
                                    Thermo Sentron Inc.,  Smiths  Industries plc
                                    and Thermo Electron Corporation. Pursuant to
                                    Item 601(b)(2) of regulation S-K,  schedules
                                    and  exhibits  to this  Amendment  Agreement
                                    have  been  omitted.   The  Company   hereby
                                    undertakes to furnish  supplementally a copy
                                    of  such   schedules  and  exhibits  to  the
                                    Commission upon request.

                           10.      $21.0 Million Promissory Note due December 
                                    15, 1998, payable to Thermo
                                    Electron Corporation.

      *          Confidential  treatment requested as to certain portions of the
                 document, which portions have been omitted and filed separately
                 with the Securities and Exchange Commission.




<PAGE>



                                   SIGNATURES

         Pursuant to the  requirements  of the Securities  Exchange Act of 1934,
the  Registrant  has duly  caused  this report to be signed on its behalf by the
undersigned thereunto duly authorized, on this 24th day of June, 1998.



                                                  THERMO SENTRON INC.


                                                  By: /s/ Melissa F. Riordan
                                                       Melissa F. Riordan
                                                       Treasurer


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             CONFIDENTIAL MATERIAL OMITTED AND FILED SEPARATELY WITH
                     THE SECURITIES AND EXCHANGE COMMISSION.
                           ASTERISKS DENOTE OMISSIONS.


                                                                    Exhibit 2.1




                             DATED 13th MARCH, 1998





                                 GRASEBY LIMITED
                      THERMO ENVIRONMENTAL INSTRUMENTS INC.
                               THERMO SENTRON INC.
                              SMITHS INDUSTRIES plc

                                       and

                           THERMO ELECTRON CORPORATION


                         ------------------------------

                                    AGREEMENT

                          for the sale and purchase of
                        all the issued share capitals of
                              GRASEBY ALLEN LIMITED
                       GRASEBY PRODUCT MONITORING LIMITED
                          GORING KERR DETECTION LIMITED
                             GRASEBY GORING KERR INC
                              GRASEBY ANDERSEN INC
                                       and
                          Part of the share capital of
                                 ALLEN FRANCE SA
                         ------------------------------







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                                    CONTENTS

Clause                                                                Page

1.       Interpretation.................................................3
2.       Sale and Purchase of the Shares................................6
3A.      Initial Consideration..........................................7
3B.      Consideration Adjustment.......................................7
3C.      Indemnity......................................................11
3D.      **** Claim.....................................................11
4.       Conditions Precedent...........................................15
5.       Covenants up to Completion.....................................15
6.       Warranties.....................................................18
7.       Tax Deed.......................................................22
8.       Completion.....................................................22
9.       Loan Accounts and Settlement of Cash Balances..................24
10.      Guarantees.....................................................25
11.      Pensions.......................................................25
12.      Protective Covenants...........................................29
13.      Change of Name.................................................31
14A.     Guarantee of the Seller's Guarantor............................33
14B.     Guarantee of the Purchasers' Guarantor.........................34
15.      Announcements..................................................35
16.      Notices........................................................35
17.      Apportionment of Further Payments..............................36
18.      General........................................................36
19.      Whole Agreement................................................38
20.      Governing Law..................................................39

Schedules

1.       Particulars of the Companies.....................................
2.       Particulars of Subsidiary Companies..............................
3.       Properties.......................................................
4.       Pensions.........................................................
5.       Agreed Accounting Principles.....................................
6.       Warranties.......................................................

Agreed Form Documents

1.     Accountants' Reports
2.     Statement of Companies' Loans
3.     Information Memoranda
4.     Statement of Seller's Loans
5.     Disclosure Letter
6.     Tax Deed
7.      Severance Costs

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                     THE SECURITIES AND EXCHANGE COMMISSION.
                           ASTERISKS DENOTE OMISSIONS.

THIS AGREEMENT is made on 13th March, 1998 BETWEEN:

     (1) GRASEBY LIMITED  registered number 894638 whose registered office is at
765 Finchley Road, London NW11 8DS (the "Seller");

     (2) THERMO ENVIRONMENTAL INSTRUMENTS INC. whose principal place of business
is   at   8   West   Forge   Parkway,   Franklin,   Massachusetts   02038,   USA
("Environmental");

     (3) THERMO  SENTRON INC. whose  principal  place of business is at 501 90th
Avenue, NW, Minneapolis, Minnesota 55433, USA ("Sentron");

     (4) SMITHS  INDUSTRIES plc registered number 137013 whose registered office
is at 765 Finchley Road, London, NW11 8DS (the "Seller's Guarantor"); and

(5)      THERMO ELECTRON  CORPORATION whose principal place of business is at 81
         Wyman Street, Waltham,  Massachusetts 02254-9046, USA (the "Purchasers'
         Guarantor").

WHEREAS:

(A)      Graseby Allen Limited  ("Allen") is a private company limited by shares
         short  particulars  of which are set out in Part A of Schedule 1 having
         an authorised  capital of  (pound)50,000  divided into 50,000  ordinary
         shares of (pound)1 all of which have been issued (the "Allen Shares").

(B)      Allen is the beneficial  owner of all the issued share capital of Allen
         Coding  Corporation  and 500 ordinary  shares in Svenska Allen AB and a
         member of the Graseby Group is the beneficial owner of 2,100 (certified
         ordinary)  shares  (the  "France  Shares")  in Allen  France SA ("Allen
         France") short details of each of which are set out in Parts A, B and C
         of Schedule 2 respectively.

(C)      Graseby Product Monitoring Limited ("Product  Monitoring") is a private
         company  limited by shares  short  particulars  of which are set out in
         Part B of Schedule 1 having an authorised  capital of  (pound)2,000,000
         divided into 1,500,000  redeemable ordinary shares of (pound)1 each and
         500,000  ordinary shares of (pound)1 each all of which have been issued
         (the "Product Monitoring Shares").

(D)      Product  Monitoring  is the  beneficial  owner of all the issued  share
         capitals of Graseby Best Limited and Graseby  Intertest  Limited  short
         particulars  of each of which are set out in Parts I and J respectively
         of Schedule 2.

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(E)      Goring Kerr Detection  Limited  ("Goring Kerr  Detection") is a private
         company  limited by shares  short  particulars  of which are set out in
         Part C of  Schedule 1 having an  authorised  capital  of  (pound)26,000
         divided into 20,000  redeemable  ordinary  shares of (pound)1  each and
         6,000  ordinary  shares of (pound)1  each all of which have been issued
         (the "Goring Kerr Detection Shares").

(F)      Graseby Goring Kerr Inc.  ("Goring Kerr") is a company  incorporated in
         the United  States of  America  under the laws of the State of New York
         short  particulars  of which are set out in Part D of Schedule 1 having
         an  authorised  share  capital of 200 common stock of no par value each
         divided into 200 shares (the "Goring Kerr Shares").

(G)      Goring Kerr Detection is the  beneficial  owner of all the issued share
         capitals  of Graseby  Goring  Kerr (NZ)  Limited,  Graseby  Goring Kerr
         Canada Inc. and Graseby  Product  Monitoring GmbH short details of each
         of which are set out in Parts D, E and F respectively of Schedule 2.

(H)      Graseby Andersen Inc. ("Andersen Inc") is a company incorporated in the
         United States of America under the laws of the State of Delaware  short
         particulars  of which  are set out in Part E of  Schedule  1 having  an
         authorised  share  capital of US$25,000  divided into 25,000  shares of
         US$1 each of which 4,886  shares have been  issued (the  "Andersen  Inc
         Shares").

(I)      Andersen Inc. is the  beneficial  owner of all the issued share capital
         of Graseby  Specac  Limited short  particulars  of which are set out in
         Part G of Schedule 2 and Graseby Specac Limited is the beneficial owner
         of all the  issued  share  capital of Graseby  Andersen  Limited  short
         details of which are set out in Part H of Schedule 2.

(J)      The Seller is beneficially entitled to all the issued share capitals of
         Allen,  Product  Monitoring,  Goring  Kerr  Detection,  Goring Kerr and
         Andersen Inc.

(K)      The Seller wishes to sell and the Purchasers wish to purchase the Allen
         Shares, France Shares, Product Monitoring Shares, Goring Kerr Detection
         Shares,  Goring Kerr Shares and Andersen Inc.  Shares (the "Shares") on
         the terms and subject to the conditions set out in this agreement.

(L)      The Seller's  Guarantor and the  Purchasers'  Guarantor  have agreed to
         guarantee  the  obligations  in this  agreement and the Tax Deed of the
         Seller and the Purchasers respectively.

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IT IS AGREED  as follows:

INTERPRETATION

(1)      In this agreement:

         "Accountants' Reports" means the financial review reports dated January
         1998 prepared by Price Waterhouse in the Agreed Form;

         "Accounts Date" means 1st October, 1997;

         "Agreed  Form"  means,  in relation to any  document,  the form of that
         document which has been initialled for the purpose of identification by
         the Seller's Solicitors and the Purchasers' Solicitors;

          "Base Rate"  means the base rate from time to time of National 
          Westminster Bank plc;

          "business  day" means a day (other than a Saturday or Sunday) when 
          banks in London are open for business;

         "Companies" means the companies  referred to in Schedule 1 and Parts A,
         and D to J inclusive, of Schedule 2 and "Company" means any of them;

         "Companies'  Loans"  means  the  sum of  (pound)12,423,740  owed by the
         Companies to members of the  Seller's  Group as set out in the document
         in the Agreed Form, to be repaid on Completion;

          "Completion"  means  completion  of the sale and  purchase of the 
          Shares in accordance with clause 8;

         "Completion  Accounts"  means the Draft  Completion  Accounts as agreed
         under clause 3B or as adjusted  following  determination of any item in
         dispute pursuant to that clause;

         "Disclosure Letter" means the letter from the Seller to the Purchasers 
          dated the date of this agreement in the Agreed Form;

         "Draft Completion Accounts" shall have the meaning assigned to it in 
          clause 3B(4);

         "Graseby Group" means the Seller and any of its subsidiaries other 
          than the Companies;

         "Indemnified  Claims"  means the  Molins  Claim and the Owens  Brockway
         Claim as described in Part I A.15 and Part IV A.15  respectively of the
         Disclosure Letter;

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         "Information  Memoranda" means the confidential  information  memoranda
         dated  December,  1997  prepared by Robert  Fleming & Co Limited in the
         Agreed Form;

         "Intellectual Property Rights" means all rights in inventions, patents,
         copyrights,  design rights,  trade marks and trade names, service marks
         (excluding  in each case the Graseby  name and any marks  incorporating
         the "Graseby"  name),  trade secrets,  know-how and other  intellectual
         property  rights   (whether   registered  or   unregistered)   and  all
         applications for them anywhere in the world;

         "Leases" means the leases in respect of each of the leasehold
          Properties;

         "Named Individuals" means each of the following persons: Stephen 
          Aubrey, Simon Bell, Neil Burdett, John Cooper, Roger Ellis, Jonathan
          Flint, David Flowerday, Carole Fyffe, Steve Holmes, Peter Mason,
         John Roberts and Steve Warren;

         "Net Assets  Statement"  means the Draft Net Assets Statement as agreed
         under clause 3B or as adjusted  following  determination of any item in
         dispute pursuant to that clause;

         "Properties"  means the properties  shortly described in Schedule 4 and
         "Property" means any of them and includes every part of each of them;

         "Purchasers" means Environmental and Sentron and "Purchaser" shall 
          mean either of them;

         "Purchasers' Group" means the Purchasers' Guarantor and all of its 
          subsidiaries, other than the Companies;

         "Purchasers' Solicitors" means Warner Cranston of Pickfords Wharf, 
          Clink Street, London SE1 9DG;

         "Seller's Accountants" means Price Waterhouse of No 1 London Bridge, 
          London;

         "Seller's Group" means the Seller's Guarantor and all of its 
          subsidiaries (other than the Companies);

         "Seller's Loans" means the sum of (pound)3,684,059  owed by one or more
         members  of the  Seller's  Group  to the  Companies  as set  out in the
         document in the Agreed Form, to be repaid on Completion;

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         "Seller's Solicitors" means Allen & Overy of One New Change, London 
          EC4M 9QQ;

         "Severance Costs" means the sum of (pound)74,525  payable in respect of
         the  termination  of the  employment  of certain  employees  of Product
         Monitoring as referred to in the list in the Agreed Form;

         "subsidiary" means a subsidiary for the purposes of section 736 of the 
          Companies Act 1985;

         "Tax Deed" means the Tax Deed in the Agreed Form; and

         "Warranties" means the warranties by the Seller contained in clause
          6(1) and Schedule 6.

(2) Any reference, express or implied, to an enactment includes references to:

         (a)      that enactment as amended, extended or applied by or under
                  any other enactment before or after this agreement;

         (b)      any enactment which that enactment re-enacts (with or without
                  modification); and

         (c)      any  subordinate   legislation  made  (before  or  after  this
                  agreement)  under any  enactment,  including one within (a) or
                  (b) above,

         save that this  subclause  shall not have  effect  insofar  as it would
         create or increase any  liability  of the Seller  under this  agreement
         beyond that at the date of this agreement.

(3)      A person shall be deemed to be connected with another if that person is
         connected  with another within the meaning of section 839 of the Income
         and Corporation Taxes Act 1988.

(4)      Words  denoting  persons shall include bodies  corporate and  
         unincorporated associations of persons.

(5)      Any  reference  to "so  far as the  Seller  is  aware"  or any  similar
         expression  shall refer to any knowledge or belief which the Seller has
         or would have if it had made all usual and reasonable enquiries of:

     (a) Terry Summers and David Blacket in respect of Allen;

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     (b) Timothy Coombs,  Thomas  Ainscough and Alice Dunn in respect of Product
Monitoring;


     (c)  Timothy  Coombs and Alice Dunn in  respect of Goring  Kerr  Detection,
Graseby Product Monitoring GmbH and Graseby Goring Kerr (NZ) Limited;

     (d) David  Johnson,  Benjamin Chu, Alice Dunn and Timothy Coombs in respect
of Goring Kerr and Graseby Goring Kerr Canada Inc.;

     (e) David Morell and Graham Young in respect of Andersen Inc.;

     (f) Andrew  Little and  Nicholas  Chamberlin  in respect of Graseby  Specac
Limited and Graseby Andersen Limited; and

     (g) Timothy Coombs,  Alice Dunn and Thomas  Ainscough in respect of Graseby
Best Limited and Graseby Intertest Limited,

     and in each of the above cases requiring such persons where  appropriate to
have made the same enquiries of the appropriate managers and senior employees in
the relevant Company.

(6)      Subclauses (1) to (5) apply unless the contrary intention appears.

(7) The headings in this agreement do not affect its interpretation.

SALE AND PURCHASE OF THE SHARES

(1)      Subject to clause 4 the Seller shall sell (or in the case of the France
         Shares shall procure the sale of) and each Purchaser shall purchase the
         Shares set out below against its name free from  encumbrances  together
         with all rights attaching to them:

     (a) Sentron:the  Allen Shares,  the France Shares,  the Product  Monitoring
Shares, the Goring Kerr Detection Shares and the Goring Kerr Shares; and

         (b)      Environmental:    the Andersen Inc. Shares.
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(2) The Seller covenants with each Purchaser that:

         (a)      it has the  right to sell and  transfer  the  full  legal  and
                  beneficial  interest  in the  Shares  (other  than the  France
                  Shares)  to each  Purchaser  and,  in the  case of the  France
                  Shares,  it has the right to procure the sale and  transfer of
                  the full  legal  and  beneficial  interest  in such  Shares to
                  Sentron, all on the terms set out in this agreement; and

         (b)      on or after  Completion  it  will,  at the  Seller's  cost and
                  expense, execute and do (or procure to be executed and done by
                  any other necessary party) all such deeds, documents, acts and
                  things as either  Purchaser  may from time to time  reasonably
                  require  in order to vest any of the  Shares  in the  relevant
                  Purchaser or as otherwise may be necessary to give full effect
                  to this agreement.

(3)      Neither  Purchaser  shall be obliged to complete the purchase of any of
         the  Shares  unless  the  purchase  of  all  the  Shares  is  completed
         simultaneously in accordance with this agreement.

3A.                      INITIAL CONSIDERATION

         The initial  consideration  for the sale of the Shares shall be the sum
         of (pound)35,260,319 (the "Initial  Consideration")  payable in cash on
         Completion and apportioned between the Shares as follows:

         (a)      for the Allen Shares, the sum of (pound)9,000,000;

         (b)      for the France Shares, the sum of (pound)70,000;

         (c)      for the Product Monitoring Shares, the sum of (pound)1,500,000
                  for   the   redeemable   ordinary   shares   and  the  sum  of
                  (pound)12,755,990 for the ordinary shares;

         (d)      for the Goring Kerr Detection Shares, the sum of (pound)20,000
                  for   the   redeemable   ordinary   shares   and  the  sum  of
                  (pound)3,980,000 for the ordinary shares;

         (e)      for the Goring Kerr Shares, the sum of (pound)1,000,000; and

         (f) for the Andersen Inc. Shares, the sum of (pound)6,934,329.

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3B.                      CONSIDERATION ADJUSTMENT

(1)      If the Net  Operating  Assets  exceed  (pound)11,244,000  the  relevant
         Purchaser  shall  (subject to the terms of this  agreement)  pay to the
         Seller by way of  deferred  consideration  for the sale of the Shares a
         sum (the  "Deferred  Consideration")  equal  to the  excess  over  that
         amount. If the Net Operating Assets are less than (pound)11,244,000 the
         Seller  shall  (subject  to the  terms  of this  agreement)  pay to the
         relevant  Purchaser by way of reduction  to the  consideration  for the
         sale of the Shares a sum (the  "Deficit")  equal to the shortfall below
         that amount.  The relevant Purchaser shall be notified to the Seller by
         the Purchasers'  Guarantor and failing such  notification  within three
         business  days  after the date on which  the Net  Assets  Statement  is
         agreed or determined under this clause the relevant  Purchaser shall be
         such Purchaser as the Seller decides.

(2)      For this purpose "Net  Operating  Assets" means the aggregate  sterling
         value of all assets (less  liabilities) of the Companies as at the date
         of Completion excluding:

         a)    all cash balances and bank overdrafts
         b)    all external borrowings
         c)    all inter company or intra-group balances, including the Seller's
               Loans and the Companies' loans but excluding those relating to 
               day to day trading activities 
         d)    all pension related assets and liabilities
         e)    all share capital and reserves
         f)    all goodwill and other intangible assets including intellectual 
               property rights

     as shown in the Net  Assets  Statement  agreed  or  determined  under  this
clause.

(3)      As  soon as  practicable  and in any  event  within  75 days  following
         Completion each Purchaser shall procure that the Companies  acquired by
         it  deliver  to that  Purchaser  the  balance  sheets as at  opening of
         business on the date of Completion (the  "Completion  Balance  Sheets")
         prepared in accordance with the convention(s) and accounting principles
         and  practices  set out in Schedule 5 ("Agreed  Rules").  Within  three
         business days of receipt of the Completion  Balance Sheets the relevant
         Purchaser  shall  deliver  the  same  to the  Seller  together  with an
         aggregated  balance sheet in which the  Completion  Balance Sheets have
         been  aggregated  ("Aggregated  Balance  Sheet").  There  shall also be
         prepared  by the  Purchasers  and  delivered  by them to the  Seller  a
         statement of cash book  balances of each of the Companies as at opening
         of business on the date of  Completion  being a summary of the balances
         on  each  of  the  Companies'   bank  accounts  (shown  by  their  bank
         statements)  adjusted to reflect  cheques  drawn but not  presented and
         deposits  made but not  reflected  on the  Companies'  bank  statements
         ("Cash Book Statements").
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(4)      Upon  receipt  of the  Completion  Balance  Sheets  and the  Aggregated
         Balance  Sheet by the Seller,  the Seller  shall  instruct the Seller's
         Accountants to prepare as soon as is reasonably  practicable and in any
         event within 45 days following receipt of the Completion Balance Sheets
         a  statement  of the  Net  Operating  Assets  (the  "Draft  Net  Assets
         Statement")  together with a report indicating their agreement with, or
         suggested  adjustments to (as the case may be) the  Completion  Balance
         Sheets and the  Aggregated  Balance Sheet and the Cash Book  Statements
         (the "Draft  Completion  Accounts") so as to make the same conform with
         the Agreed Rules.

(5)      The Purchaser shall procure that the Seller's Accountants are given all
         such  access  to the  premises  and  financial  and other  records  and
         documents  of the  Companies  as  are  necessary  for  the  purpose  of
         preparing  the  Draft Net  Assets  Statement  and the Draft  Completion
         Accounts and shall  procure that the  directors  and  employees of each
         Company promptly provide the Seller's  Accountants with all information
         and explanations as they may reasonably request in connection with such
         preparation and determination.

(6)      The  Seller  shall  deliver  to  each  Purchaser  a copy  of the  Draft
         Completion  Accounts  and  Draft  Net  Assets  Statement  within  three
         business days after they are prepared.

(7)      Within 14 days of delivery of the Draft  Completion  Accounts and Draft
         Net Assets  Statement  as referred  to in  subclause  (6) above  either
         Purchaser  may  notify  the Seller in writing of any item or items they
         wish to dispute.  If no such  notice is  received by the Seller  within
         such 14 day period the  Purchasers  shall each be deemed to have agreed
         the Draft Completion Accounts and the Draft Net Assets Statement.

(8)      Upon  receipt  by the  Seller  of a notice  of any item of  dispute  in
         accordance  with  subclause  (7)  above  the  Seller  and the  relevant
         Purchaser  shall  use all  reasonable  endeavours  to agree  the  Draft
         Completion  Accounts  and the Draft Net  Assets  Statement  in  writing
         within 14 days of  delivery of such  notice  failing  which the item or
         items in dispute shall be determined by:

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     (a) such firm of chartered accountants as the parties may agree in writing;
or

     (b) failing agreement on the identity of the firm of chartered  accountants
within a further seven days from the expiry of the period of 14 days referred to
above,  such firm of independent  chartered  accountants as may be appointed for
this purpose on the  application of any party to this agreement by the President
for the time being of the  Institute  of  Chartered  Accountants  in England and
Wales.

     (9) The accountants appointed under subclause (8) above (the "Accountants")
shall act on the following basis:

         (a)      the Accountants shall act as experts and not as arbitrators;

         (b)      their terms of reference shall be to determine, within 30 days
                  of  their  appointment,  an  amount  which  in  their  opinion
                  represents  under and in accordance  with the Agreed Rules the
                  item or items in  dispute,  as  notified to them in writing by
                  either the relevant Purchaser(s) or the Seller;

         (c)      the  Seller  and  the   Purchasers   shall  each  provide  the
                  Accountants with all information which they reasonably require
                  and the  Accountants  shall be  entitled  (to the extent  they
                  consider  it  appropriate)  to  base  their  opinion  on  such
                  information  and on the  accounting  and other  records of the
                  Companies;

     (d) the  determination of the Accountants shall (in the absence of manifest
error) be conclusive; and

         (e) their costs shall be borne equally between the parties.

(10)     The amount of any Deferred  Consideration  or Deficit,  as the case may
         be,  together  with accrued  interest  calculated  in  accordance  with
         subclause  (12)  shall be payable  within  seven days of the Net Assets
         Statement being agreed or ascertained under the above  provisions.  The
         amount of such Deferred  Consideration or Deficit,  shall be reduced or
         increased as the case may be by an amount equal to 69 per cent.  of the
         Severance  Costs to the extent that such Severance  Costs have not been
         paid before  Completion.  At the same time, the Purchasers shall pay to
         the  Seller  by way of  additional  consideration  for the  sale of the
         Shares a sum equal to the amount (if any) by which the aggregate of the
         cash balances as shown on the Cash Book Statements exceeds the sum paid
         on account under clause 9(3). If such  aggregate cash balances are less
         than the sum paid on account under clause 9(3),  the Seller shall repay
         to the Purchasers a sum equal to the shortfall.

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(11)     If a Purchaser has notified the Seller of a bona fide Warranty Claim in
         accordance  with  the  provisions  of this  agreement  then it shall be
         entitled to deduct the amount of such Warranty  Claim from any Deferred
         Consideration  due to the  Seller and pay it into an  interest  bearing
         escrow  trust  account  to be  opened  jointly  in the  names  of  that
         Purchaser and the Seller.  Upon settlement or  determination by a court
         of such Warranty  Claim the amount (if any) of the Warranty  Claim that
         is  agreed  between  the  Seller  and that  Purchaser  or is  otherwise
         determined  as  being  due to that  Purchaser  shall be  repaid  to the
         Purchaser  (together  with  interest  accrued  thereon) from the escrow
         account and any balance (together with interest accrued thereon) in the
         escrow account shall be paid to the Seller.

(12)     Interest  shall  accrue  on a daily  basis on the  amount  of  Deferred
         Consideration  or  Deficit  (as the case may be) at the rate of two per
         cent.  above the Base Rate for the period  from the date of  Completion
         until  payment  is made in  accordance  with this  clause  (both  dates
         inclusive).

3C.                      INDEMNITY

     (1)  The  Seller  agrees  to  indemnify  and  hold  harmless  the  relevant
Purchasers  against 50 per cent. of all liabilities,  costs and expenses arising
out of the Indemnified Claims.

     (2) The relevant Purchasers shall take such action to avoid, dispute,
         resist, appeal,  compromise or contest the liability of the Indemnified
         Claims as may  reasonably  be  requested by the Seller and shall ensure
         that the Companies  co-operate  with the Seller in relation to the same
         and give the Seller full and prompt access to their relevant employees,
         documents,  records and  premises  where  reasonably  requested  by the
         Seller.

3D.  **** CLAIM

     (1) The Seller shall  indemnify  Product  Monitoring in respect of the ****
Claim on the terms of this clause.

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(2)      The  Seller  and  Sentron  shall  regularly  consult  with  each  other
         regarding  developments  in  respect  of the ****  Claim  and,  without
         prejudice to subclause (3), shall co-operate  together with a view to a
         satisfactory  resolution  thereof  and  with a view to  minimising  the
         adverse effect of the **** Claim on the business of Product Monitoring.

(3)      Sentron shall procure that the Seller shall have the exclusive  conduct
         on behalf of Product  Monitoring of all  negotiations,  discussions and
         legal  proceedings  between Product  Monitoring and **** relating to or
         arising out of the **** Claim including  negotiations  for the grant by
         **** to Product Monitoring of a licence to use the Patent (such licence
         to be for a term not  expiring  before  **** and  otherwise  upon terms
         (save  as to  payments  due to ****  thereunder  by way of  royalty  or
         similar   such   payments)   reasonably   satisfactory   to   Sentron).
         Accordingly, Sentron shall procure that Product Monitoring shall:

         (a)      co-operate  with  the  Seller  and keep  the  Seller  promptly
                  informed of all  communications  received from **** in respect
                  of the **** Claim;

         (b)      give the Seller  full access at all  reasonable  times to, and
                  copies of, relevant documents, records, employees and premises
                  for purposes relating to the **** Claim;

         (c)      immediately upon request by the Seller undertake with **** not
                  to make any further  sales of the **** in the United States of
                  America;

         (d)      within seven days of any request by the Seller,  cease to make
                  any further sales of the **** in the United States of America;

         (e)      cease  to make  sales of such  **** in the  United  States  of
                  America if an  injunction  is granted to **** which  restrains
                  such sales by Product Monitoring;

         (f)      enter  into such  licence  to use the Patent as the Seller may
                  agree, on Product  Monitoring's  behalf, with **** (subject to
                  the foregoing  provisions of this  subclause in respect of the
                  terms of such licence); and

         (g)      not  admit,  settle or  compromise  the **** Claim or take any
                  action  in  connection  with  the  ****  Claim  other  than as
                  directed by the Seller.

(4) The Seller shall cease to be liable under this clause immediately upon:

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     (a) Sentron failing to comply with subclause (3)(c)(d) or (e) above; or

         (b)      the  Patent   being   determined   by  a  court  of  competent
                  jurisdiction or regulatory body to be not valid; or

         (c)      Product  Monitoring  voluntarily  ceasing to endeavour to make
                  sales of the **** in the United States of America; or

         (d)      Product Monitoring agreeing a full and final settlement of the
                  ****  Claim  with  ****  (provided  all  costs,  expenses  and
                  liability  in  respect  of such  settlement  are  borne by the
                  Seller),

         save (i) for any  liabilities  which the Seller may have incurred under
         this clause up to the time of the event in (a), (b), (c) or (d) of this
         subclause  and (ii) that the Seller  shall bear any costs  incurred  by
         Product  Monitoring at the Seller's direction in resisting the validity
         of the Patent to the extent  that such costs are not  recoverable  from
         **** following the  determination  referred to in paragraph (b) of this
         subclause.

(5)      If the Seller, on behalf of Product Monitoring, procures the grant of a
         licence  from **** (which  shall be on the terms  outlined in subclause
         (3) above) to Product Monitoring to use the Patent up to ****:

     (a) Sentron  shall  procure that Product  Monitoring  shall comply with the
terms of such licence;

         (b)      provided Sentron complies with paragraph (a) above, the Seller
                  shall bear any royalty fees and other similar payments payable
                  under such licence;

         (c)      save as provided in paragraph (b) and without prejudice to any
                  liabilities  of the Seller under this clause accrued up to the
                  effective date of such licence, the Seller shall cease to have
                  any further liability under this clause.

(6)      Without  prejudice  to the other  provisions  of this clause other than
         subclause  (1),  the  Seller's  liability  under this  clause  shall be
         limited as follows:

         (a)      any costs and expenses of legal  advisers or patent  attorneys
                  or agents  engaged by Sentron  or Product  Monitoring  to deal
                  with the **** Claim shall be borne by the Seller,  but only to
                  the extent previously agreed in writing by the Seller;

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         (b) the  Seller  shall  bear any  liability  which  Product  Monitoring
either:

                  (i)      agrees  in  writing  with  **** as its  liability  in
                           respect of the **** Claim provided Product Monitoring
                           has acted in  accordance  with the  Seller's  written
                           directions in making such agreement; or

                  (ii)     is  determined  by a court of competent  jurisdiction
                           (where no appeal can be made or the Seller elects not
                           to pursue such  appeal) to have to **** in respect of
                           the **** Claim;

         (c)      if Product  Monitoring is obliged by an injunction issued by a
                  court of  competent  jurisdiction  or by  agreement  with ****
                  (entered  into at the direction of the Seller) or by direction
                  of the Seller issued under  subclause  (3)(d) to cease selling
                  the **** in the United States of America, the Seller shall pay
                  to Product Monitoring:

                  (i)      a sum equal to  US$****  per day for the period (the
                           "Shutdown  Period")  from the date of such  cessation
                           until the  earlier  of (i) **** and (ii) the date (if
                           any) on which Product  Monitoring is permitted  under
                           such injunction or agreement (but not such direction)
                           to recommence  sales of the **** in the United States
                           of America; and

                  (ii)     US$**** if the Shutdown Period is four months or 
                           more; and

                  (iii) a  further  US$****  if the  Shutdown  Period  is six
months or more.

(7)      The  Seller's  liability  under this clause shall cease on **** save in
         respect of any such liability accrued before that date.

(8)      For the avoidance of doubt, no payments by the Seller under this clause
         shall  constitute  a  reduction  in the  consideration  payable for the
         Product Monitoring Shares.

(9) For the purposes of this clause 3D the following  expressions shall have the
following meaning:

         "****" means ****;
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     "**** Claim" means the alleged  claim by **** that the ****  infringes  the
Patent;

         "Patent" means ****'s patent (US **** of ****); and

     "****" means the **** of Product Monitoring the subject of the **** Claim.

4.    CONDITIONS PRECEDENT

     (1) The sale and purchase of the Shares is conditional on:

         (a)      the  necessary   regulatory   filing  having  been  made,  all
                  appropriate   waiting  periods  and  any  other  time  periods
                  (including   extensions   thereto)  under  the  United  States
                  Hart-Scott-Rodino Antitrust Improvements Act 1976 (as amended)
                  and the regulations made thereunder having expired,  lapsed or
                  been  terminated  in  respect of the  change of  ownership  of
                  Goring Kerr and Andersen Inc.; and

         (b)      the  necessary  regulatory  filing  having  been  made and the
                  parties  having  obtained  formal  clearance  from the  German
                  Federal Cartel Office in respect of the change of ownership of
                  Graseby Product Monitoring GmbH.

     (2) The Purchasers may waive either or both of the conditions (a) to (b) in
subclause  (1) above in whole or in part at any time by notice in writing to the
Seller.

     (3) Each of the parties shall use reasonable endeavours to procure that the
conditions  in subclause (1) above are fulfilled on or before 15th May, 1998 and
each of the parties agrees to assist in the preparation of all necessary filings
with,  attending  meetings  with or speaking to (if  necessary)  the  regulatory
authorities referred to in subclause (1) above.

     (4) If the conditions in subclause (1) above are not fulfilled or waived on
or  before  the date  specified  in  subclause  (3) all of the  clauses  of this
agreement  shall cease to have effect  (save in respect of  subclause  (3),  and
clauses 1, 15, 16,  18(5),  19 and 20 which shall  survive  termination  of this
agreement).

5.        COVENANTS UP TO COMPLETION

(1)      In the period from the date of this  agreement  until  Completion,  the
         Seller shall  (insofar as it is within its power to do so) procure that
         except with the prior consent of the Purchasers:

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     (a) none of the  Companies  departs from the ordinary  course of its day to
day trading in any material respect;

     (b) none of the rights  attached to any shares in any Company is  modified,
no shares in any  Company  are  created or issued,  no option or rights over any
shares or uncalled capital of any Company is granted or agreed to be granted and
no obligations convertible into shares are created;

     (c) no alteration is made to the  memorandum or articles of  association of
any Company;

     (d) none of the Companies will:

     (i) incur any expenditure exceeding (pound)500,000 on capital account;

     (ii) declare, make or pay any dividend or other distribution;

     (iii) make any material  changes in the terms and  conditions of employment
of any of its senior  employees or employ or  terminate  (except for good cause)
the  employment  of any such  person (and for the  purposes of this  subclause a
senior employee shall mean a person earning more than (pound)40,000 per annum);

     (iv) permit any of its  insurances to lapse or knowingly do anything  which
would make any policy of insurance  void or voidable or materially  increase the
level of cover provided under such insurance policies;

     (v) admit any person  (other than  pursuant to this  agreement)  whether by
subscription or transfer or transmission as a member of that Company;

     (vi)  give  any  guarantee  or  indemnity  other  than  in  respect  of the
obligations of another Company or in the ordinary course of business;

     (vii)  acquire  any  shares  of any other  company  or  participate  in any
partnership or joint venture or agree to do so;

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     (viii) permit the  appointment of any person as a director of that Company;
or

     (ix)  discontinue or amend the Seller's  Scheme (other than as envisaged in
Schedule  4) or  commence  to  wind it up or  cease  to  admit  new  members  or
communicate to any employee any intention to do so; or

     (c) it will not  dispose  of any  interest  in the Shares or any of them or
grant any option or right of pre-emption over, or mortgage,  charge or otherwise
encumber the Shares or any of them.

(2)       Prior  consent  requested  from the  Purchasers  by the  Seller  under
          subclause (1) shall not be unreasonably withheld or delayed by the 
          Purchasers.

(3)      The  requirement  for consent shall not apply and this clause shall not
         be breached if (i) the Seller can demonstrate that it was necessary for
         it to take  the  relevant  action  without  obtaining  the  Purchasers'
         consent  first  due  to  emergency   requirements   which  would  cause
         significant  operational  difficulties  if not  remedied  before it was
         practicable to consult with and obtain consent of the  Purchasers;  and
         (ii) the Seller  notifies the  Purchasers of such action as soon as the
         Seller is reasonably able to do so.

(4)      Each  Purchaser  and any person whom it may  authorise for this purpose
         shall be allowed access upon reasonable notice to all the books and the
         records,  agreements and other documents and premises  belonging to any
         Company and the Seller shall supply any information reasonably required
         by the Purchaser relating to any Company.

(5)      The Seller shall in so far as it is able, use its reasonable endeavours
         (including  by  exercising  its  voting  rights)  to  ensure  that  the
         provisions of this clause are complied with in respect of Svenska Allen
         AB and Allen France as if each of them were a Company.

(6)      In the period  between the date of this agreement and  Completion,  the
         Purchasers  will use their  best  endeavours  to assist  the  Seller in
         procuring  that the  employment  contracts of A. Dunn, T. Coombs and T.
         Ainscough are transferred  from the Seller to Product  Monitoring,  and
         the  employment  contracts of G.R.  Young and R. White are  transferred
         from the Seller to Andersen Inc.

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6.        WARRANTIES

(1)      The Seller warrants to the Purchasers that save as fairly  disclosed in
         the  Disclosure  Letter each of the statements set out in Schedule 6 is
         true. The Seller  acknowledges  that the  Purchasers  have entered into
         this agreement in reliance upon,  amongst other things,  the Warranties
         and the  undertakings in clause 12. Save as provided in this agreement,
         the  Warranties  shall be  separate  and  independent  and shall not be
         limited  by  reference  to any  other  paragraph  in  Schedule  6 or by
         anything else in this agreement or the Tax Deed.

(2)      The Seller agrees with the  Purchasers  for  themselves and as trustees
         for each  Company  and  their  respective  employees  to  assign to the
         Purchasers  any  rights or claims  which it may have in  respect of any
         misrepresentation, inaccuracy or omission in or from any information or
         advice  supplied or given by any of the Companies or their employees in
         connection  with the giving of the Warranties and the  preparation  and
         entry into of this  agreement,  the Tax Deed and the Disclosure  Letter
         save that this shall not apply in case of fraud or in  relation  to any
         person who has ceased to be such an employee.

(3) The Purchasers acknowledge and agree that:

         (a)      the Warranties and the other  provisions of this agreement are
                  the only  warranties or other  assurances of any kind given by
                  or on behalf of the  Seller  and on which the  Purchasers  may
                  rely in entering into this agreement;

         (b)      no other  statement,  promise or forecast made by or on behalf
                  of the  Seller  may  form  the  basis  of,  or be  pleaded  in
                  connection  with,  any  claim  by  a  Purchaser  under  or  in
                  connection with this agreement; and

         (c)      any claim by a Purchaser or any person  deriving title from it
                  in connection  with the Warranties (a "Warranty  Claim") shall
                  be subject to the following provisions of this clause.

(4)      There shall be  disregarded  for all  purposes  any  Warranty  Claim in
         respect  of which the  amount of the  damages  to which the  Purchasers
         would otherwise be entitled is less than (pound)5,000; provided however
         that a series of related  claims or claims  based on the same facts and
         circumstances  shall for the purposes of this subclause be deemed to be
         a single  claim and the  damages in respect of each such claim shall be
         aggregated in determining whether they exceed (pound)5,000.

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(5) The liability of the Seller in respect of the Warranties:

     (a) shall not (when aggregated with any liability under the Tax Deed) arise
unless the amount of all claims made in respect of the Warranties and/or the Tax
Deed (or which would have been made but for the  operation of this  paragraph or
the  corresponding  provision  in the Tax Deed and  excluding  also those claims
referred to in subclause  (4))  exceeds(pound)500,000  but if liability  exceeds
that  figure  then all claims  including  claims  previously  notified  shall be
counted and for this  purpose any  reduction  in such claim  resulting  from the
operation  of clause 8(4) of the Tax Deed shall not prevent the  Purchaser  from
being able to make a Warranty  Claim should the reduced  level of such  Warranty
Claim be less than(pound)500,000; and

         (b)      shall not (when  aggregated  with any liability  under the Tax
                  Deed) exceed the aggregate amount of the Initial Consideration
                  as  adjusted  pursuant  to clause  3B and any sums paid  under
                  clauses 9(3) and 3(10); and

         (c)      shall not arise to the extent  that the matter  giving rise to
                  the breach is the subject of a claim under the Tax Deed.

(6)      The Seller shall cease to have any liability under or in respect of the
         Warranties 18 months after the date of Completion  except in respect of
         a Warranty Claim of which a Purchaser gives notice to the Seller before
         the expiry of such period and in  accordance  with  subclause (8) below
         but the liability of the Seller in respect of any Warranty  Claim shall
         absolutely  terminate  if  proceedings  in  respect of it have not been
         commenced  and served on the Seller  within  nine  months of service of
         notice of that Warranty Claim.

(7) Neither Purchaser shall be entitled to make any Warranty Claim:

         (a)      to the extent that  provision or  allowance  for the matter or
                  liability  which  would  otherwise  give  rise to the claim in
                  question  has been made or falls to be made in the  Completion
                  Accounts or it is otherwise taken account of, or reflected in,
                  the Completion Accounts;

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         (b)      if the  claim  would  not  have  arisen  but for a  change  in
                  legislation  made  after  Completion   (whether   relating  to
                  taxation, rates of taxation or otherwise) or the withdrawal of
                  any extra-statutory  concession  previously made by the Inland
                  Revenue  or any other  taxing  authority  (whether  or not the
                  change purports to be effective retrospectively in whole or in
                  part); or

         (c)      to the extent  that the claim  arises as a result  only of any
                  change after Completion in the accounting bases upon which any
                  of the Companies values its assets.

(8)      If a Purchaser or any of the Companies  becomes aware of a matter which
         could give rise to a Warranty Claim that Purchaser shall give notice of
         the relevant facts to the Seller as soon as reasonably  practicable and
         in any event within 30 days of that  Purchaser  becoming aware of those
         facts and (subject to the provisions of the Tax Deed in relation to any
         matter  which may form the subject of a claim under it) if the claim in
         question is as a result of or in connection with a liability or alleged
         liability to a third party that  Purchaser  (at the  Seller's  expense)
         shall procure the Companies or the relevant one or more of them to take
         such action to avoid, dispute,  resist,  appeal,  compromise or contest
         the  liability as may  reasonably  be requested by the Seller  provided
         that nothing in this clause 6(8) shall oblige the relevant Purchaser to
         take any action  which might  reasonably  be expected to be  materially
         prejudicial  to the  business  of the  Company.  In any case  where the
         relevant  Purchaser  is not so obliged to take or procure the taking of
         any action,  and liability on the Seller either arises under a Warranty
         Claim or is  greater  than it would  have been if such  action had been
         taken,  the  Seller  shall  not be  liable in  respect  of either  such
         Warranty  Claim or to the extent that such liability is greater than it
         so would have been.

(9)      Without  prejudice  to the  Purchasers'  duty to  mitigate  any loss in
         respect  of any breach of the  Warranties,  if in respect of any matter
         which would  otherwise  give rise to a breach of the  Warranties one of
         the  Companies is entitled to claim under any policy of  insurance  (or
         would have been so  entitled  had it  maintained  in force its level of
         insurance cover current at Completion)  the amount of insurance  monies
         which  that  Company  actually  recovers  shall  reduce  pro  tanto  or
         extinguish  the claim for breach of the  Warranties  and the Purchasers
         undertake to use their reasonable endeavours to recover such monies.

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(10)     If the Seller  makes any  payment  by way of damages  for breach of the
         Warranties  (the  "Damages  Payment")  and any of the  Companies or the
         Purchasers  receives any benefit  otherwise  than from the Seller which
         would not have been  received but for the  circumstance  giving rise to
         the  claim in  respect  of which  the  Damages  Payment  was made  that
         Purchaser  shall,  once it or the relevant  Company has  received  such
         benefit, forthwith repay to the Seller an amount equal to the lower of:
         (i) the amount of such benefit (less any  reasonable  costs or expenses
         incurred by the  relevant  Purchaser  or a Company in  recovering  such
         benefit); and (ii) the Damages Payment.

(11)     To the extent that the  Purchasers or the Companies do any act or thing
         after Completion  (other than in the ordinary course of business of the
         Companies  or as required by law) which gives rise to a Warranty  Claim
         which  would not  otherwise  arise where the  Purchasers  were aware or
         ought  reasonably  to have been aware such act or thing would be likely
         to give rise to a Warranty Claim,  the Purchasers  shall not be able to
         recover any sums in respect of such Warranty Claim.

(12)     Any payment made by the Seller in respect of a breach of the Warranties
         or a liability  under the Tax Deed shall be deemed to be a reduction in
         the consideration paid for the Shares.

(13)     The  provisions  of this clause shall have effect  notwithstanding  any
         other provisions of this agreement.

(14)     None of the limitations  contained in clauses 6(4) to 6(12) shall apply
         to any claim  which  arises as the  consequence  of, or is delayed as a
         result of fraud by the Seller or by any member of, or  employee  of any
         member of, the Seller's Group.

(15) Each of the Purchasers and the Purchasers' Guarantor warrants to the Seller
that:

         (a)      they are  corporations  validly existing under the laws of the
                  state  of  their   incorporation   with  requisite  power  and
                  authority  to enter  into and  perform,  and  have  taken  all
                  necessary  corporate  action to authorise  the  execution  and
                  performance  of,  their  respective   obligations  under  this
                  agreement and the Tax Deed;

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         (b)      this   agreement  and  the  Tax  Deed  will,   when  executed,
                  constitute  valid  and  binding  obligations  of  each  of the
                  Purchasers and the Purchasers'  Guarantor  enforceable against
                  them in accordance with their terms; and

         (c)      other   than   as   contemplated   by   this   agreement,   no
                  announcements,  consultations, notices, reports or filings are
                  required to be made by any member of the Purchasers'  Group in
                  connection   with  the   transactions   contemplated  by  this
                  agreement  nor are  any  consents,  approvals,  registrations,
                  authorisations  or  permits  required  to be  obtained  by any
                  member  of  the  Purchasers'  Group  in  connection  with  the
                  execution and  performance  of this  agreement or the Tax Deed
                  the failure to make or obtain any of which would:

                  (i)      prevent or delay completion of this agreement; or

                  (ii)     subject the Seller to any liability.

(16)     Without prejudice to subclause (5)(a) above the liability of the Seller
         in  respect of any  Warranty  Claim or a  liability  under the Tax Deed
         shall be reduced pro tanto or extinguished altogether,  as appropriate,
         to the extent of any overprovision determined in accordance with clause
         8 of the Tax Deed.

7.        TAX DEED

         The Seller shall on  Completion  enter into a Tax Deed in favour of the
Purchasers.

8.        COMPLETION

(1)      Completion  shall take place at the offices of the Seller's  Solicitors
         as soon as practicable  after and in any event within two business days
         after  satisfaction  (or waiver) of the conditions in clause 4(1) or on
         such other date as the Seller and the Purchasers may agree in writing.

(2) At Completion the Seller shall procure:

         (a)      the delivery to the Purchasers of:

                  (i)      duly executed  transfers in favour of the  Purchasers
                           or their  nominee(s)  of the  Allen  Shares,  Product
                           Monitoring Shares and Goring Kerr Detection Shares;

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                  (ii)     the share certificates representing the Allen Shares,
                           Product Monitoring Shares and Goring Kerr Shares;

                  (iii)    a duly executed  transfer ("ordres de mouvements") in
                           favour of the  Purchaser  in  respect  of the  France
                           Shares;

                  (iv)     stock certificates representing the Goring Kerr 
                           Shares and the Andersen Inc. Shares duly endorsed by 
                           the Seller in favour of the Purchaser;

                  (v)      the  certificates  of  incorporation,   common  seal,
                           minute books,  cheque books,  statutory registers and
                           share certificate books of the Companies;

                  (vi)     the title deeds and documents, relating to the 
                           Properties, that are in the Seller's possession;

                  (vii)    the Tax Deed duly executed by the Seller;

                  (viii)   the  resignations  of Alan Smith and Neil  Burdett as
                           directors  and/or  secretaries of the  Companies,  in
                           each case acknowledging by way of deed that they have
                           no claim  against the  Companies  whether for loss of
                           office or otherwise;

                  (ix)     the  resignation of the auditors of each Company with
                           acknowledgements  by them  that  they  have no  claim
                           against  the  Company  and,  where  applicable,   the
                           statement referred to in section 394 of the Companies
                           Act   1985  to  the   effect   that   there   are  no
                           circumstances  connected with their resignation which
                           they consider  should be brought to the notice of the
                           members or creditors of the Company; and

                  (x)      evidence reasonably satisfactory to each of the 
                           Purchasers that it has repaid the Seller's Loans;

         (b) that board  meetings of each of the  Companies are held at which it
is resolved that:

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                  (i)      the resignations  referred to in paragraph  (a)(viii)
                           are duly  accepted  and such  persons as the relevant
                           Purchaser   nominates  are  appointed  as  additional
                           directors and secretaries of the Companies;

                  (ii)     their registered offices are changed as the 
                           Purchasers require;  and

                  (iii)    the transfers  referred to in paragraph  (a)(i) above
                           (subject  only  to  their  being  duly  stamped)  are
                           approved for registration.

(3)      Upon completion of the matters referred to in subclause (2) above the 
         Purchasers shall:

         (a)      procure the repayment of the Companies Loans by or on behalf 
                  of the Companies and pay the Initial Consideration to the 
                  Seller; and

         (b) deliver to the Seller a duly executed counterpart of the Tax Deed.

(4)      The Purchasers agree that as soon as practicable  following  Completion
         they will  assist the Seller to remove  from the 401K Plan of  Andersen
         Inc the  entitlements  of any  employees of any members of the Seller's
         Group,  with any costs of such removal being borne by the Seller to the
         extent that it has not been completed by the date of Completion.

9.        LOAN ACCOUNTS AND SETTLEMENT OF CASH BALANCES

(1)      Any sums owed at Completion by any member of the Seller's  Group to any
         Company  or vice  versa  in  respect  of  trading  between  them in the
         ordinary  course of business shall be discharged in accordance with the
         terms previously agreed between them.

(2)      It is  acknowledged  by each of the Purchasers  that in preparation for
         the sale of the Companies the Seller has  re-organised  the  Companies'
         banking  arrangements  and  details  of all  these  changes  have  been
         disclosed to them in the Disclosure Letter.

(3)      Within five days from the date of  Completion  the  Purchasers  shall
         deliver to the Seller a bank statement as at the opening of business on
         the  date of  Completion  for  each  bank  account  in the name of each
         Company (the  "Completion  Bank  Statements")  and pay to the Seller as
         additional  consideration for the sale of the Shares an amount equal to
         the  aggregate  of the  cash  balances  shown  on the  Completion  Bank
         Statements. For this purpose, all such cash balances shall be converted
         into sterling from the relevant currency at the prevailing spot rate of
         exchange of that currency as published in the  Financial  Times (London
         edition) the next business day after Completion.


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10.       GUARANTEES

(1)      The Seller shall procure that on or as soon as  reasonably  practicable
         after  Completion  the Companies are released from all  guarantees  and
         indemnities  (if any) given by them in respect of any obligation of any
         member of the Seller's Group.

(2)      The  Purchasers  shall  procure  that  on  or  as  soon  as  reasonably
         practicable  after  Completion  each  member of the  Seller's  Group is
         released from all  guarantees and  indemnities  (if any) given by it in
         respect of any obligation of any of the Companies and pending each such
         member's  release the Purchasers shall indemnify the Seller (for itself
         and as trustee  for each such  member)  against all  liabilities  under
         those guarantees and indemnities.

11.                      PENSIONS

(1)      The parties  shall comply with the  provisions of Schedule 4 applicable
         to  them  ("Schedule")  and  the  Purchasers  shall  procure  that  the
         principal  employer of the  Purchaser's  Scheme  shall  comply with the
         provisions  of this  clause  and such  Schedule  applicable  to it. All
         expressions  used in this  clause  have  the  same  meaning  as in that
         Schedule  except that  "Transfer  Amount"  means the greater of A and B
         where:

         A is the Transfer Amount defined in the Schedule;

         B is the  aggregate  of (a), (b) and (c) below  adjusted in  accordance
with (d) below:

         (a)      The amount which the Transfer  Amount  defined in the Schedule
                  would have been if the unadjusted  Transfer Amount,  excluding
                  the amount referred to in paragraph 7 of the Actuary's Letter,
                  had been calculated using a valuation rate of interest of nine
                  per cent.  per annum,  a rate of general pay  inflation of six
                  per cent. per annum and a market value  adjustment of 3.03 per
                  cent  divided by the net yield on the  FT-Actuaries  All Share
                  Index on the Membership Transfer Date.

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         (b)      The capital value,  calculated on the same basis as the amount
                  in (a) above,  at Membership  Transfer Date of the  Consenting
                  Members'  normal  contributions  to  the  Seller's  Scheme  in
                  accordance  with the Rules for the period up to 31st December,
                  1999.

         (c)      The capital value,  calculated on the same basis as the amount
                  in (a) above,  at Membership  Transfer Date of the  difference
                  between  an  employer's  contribution  rate  for the  relevant
                  Company  of nine  point  five per cent.  and six per cent.  of
                  Salary  in  respect  of each  Consenting  Member  for a period
                  starting on the  Membership  Transfer Date and ending 10 years
                  and 4 months after the date of Completion.

         (d)      The  aggregate  of (a),  (b) and (c)  above  is  increased  or
                  decreased  by  the  Investment   Adjustment  over  the  period
                  starting on the Membership Transfer Date and ending at the end
                  of the day which is three days before the Actual  Payment Date
                  and then  increased  by  interest at the Agreed Rate from (and
                  including)  the day which is 3 days before the Actual  Payment
                  Date  until the end of the day  immediately  before the Actual
                  Payment Date.

(2)      If the Transfer  Amount is not  transferred in full to the  Purchaser's
         Scheme  within one month after the Due Payment  Date the Seller  shall,
         subject to subclauses  (3) and (4) below,  forthwith  upon receipt of a
         written demand from either Purchaser,  pay to the relevant  Purchasers,
         by way of  reduction to the  consideration  for the sale of the Shares,
         the following amount:

         (i)      if some assets have been  transferred from the Seller's Scheme
                  to the  Purchaser's  Scheme  (whether  before  or  after  that
                  written demand is received) - the amount by which the Transfer
                  Amount  (calculated  as at the date on which those assets were
                  transferred)  exceeds the value so transferred  but the excess
                  for this purpose shall:

                  (a)      be the excess  adjusted by the Investment  Adjustment
                           from (and  including) the date of that transfer up to
                           (but  excluding)  the date of  payment  by the Seller
                           pursuant to this sub-paragraph; and

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                  (b)      be reduced  (after the adjustment in (a)) if, despite
                           some   assets   having   been   transferred   to  the
                           Purchaser's Scheme, any benefit remains payable to or
                           in respect of a Consenting  Member under the Seller's
                           Scheme; the reduction will be by the aggregate of the
                           cash equivalents of those benefits.

         (ii)     if no assets have been transferred from the Seller's Scheme to
                  the  Purchaser's  Scheme - the  amount by which  the  Transfer
                  Amount  (calculated as at the date on which payment is made to
                  the relevant Purchasers in accordance with this subclause (2))
                  exceeds the aggregate of the cash  equivalents of the benefits
                  remaining  payable to or in respect of the Consenting  Members
                  under the Seller's  Scheme when payment is made in  accordance
                  with this subclause (2);

         less (in either case):

         (iii)      any amount due from the Purchasers or the relevant Company 
                    to the Seller or the Seller's Scheme under the Schedule; and

         (iv)     any amount, in addition to the amount transferred  referred to
                  in (i)  above,  transferred  from the  Seller's  Scheme to the
                  Purchaser's Scheme before payment under this sub-clause (2) is
                  made adjusted by the  Investment  Adjustment  from the date of
                  transfer to the date of such payment.

         The amount  derived under (i) to (iv) above is referred to below as the
"Shortfall".

(3)      If any of the Transfer  Conditions ceases to be fulfilled or effective,
         the relevant  Purchasers  shall not demand payment under  subclause (2)
         above and the time limit  referred to in  subclause  (2) above will not
         commence,  or (if any of the Transfer  Conditions cease to be fulfilled
         or  effective  after  the  time  limit  has  started  to  run)  will be
         suspended, until all those conditions are again fulfilled or effective.

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(4)      No payment shall be paid by the Seller under subclause (2) above:

         (i)      if the  reason  for the  Transfer  Amount  (or part of it) not
                  having been  transferred to the Purchaser's  Scheme is because
                  of the  continuing  failure  of  the  Purchaser's  Scheme  for
                  whatever  reason  to  accept  the  whole  or any  part  of the
                  Transfer  Amount or if the reason is any other reason  outside
                  the control of the  Seller's  Scheme but, if no payment is due
                  from the  Seller  because  of any such  reason,  payment  will
                  become due (subject to the other provisions of this clause) if
                  and when such reason ceases to exist;

         (ii)     unless the  Purchasers  undertake  in writing to the Seller to
                  pay the Shortfall  forthwith to the Purchaser's  Scheme and to
                  procure that such amount be applied by the Purchaser's  Scheme
                  to provide  benefits for the Consenting  Members in respect of
                  their  Pensionable  Service in the Seller's  Scheme before the
                  Membership  Transfer Date to the extent  required by paragraph
                  3(D) of the Schedule only.

(5)      If payment is made by the Seller in accordance with subclause (2) above
         the amount of that payment will be deducted  from the amount  otherwise
         payable under paragraph 6(A) of the Schedule.

(6) If the Seller pays the Shortfall to the Purchasers then:

         (i)      forthwith  following  the Seller  making  payment  pursuant to
                  subclause  (2)  above the  Purchasers  shall  procure  that an
                  amount  equal to the  Shortfall  shall be  contributed  to the
                  Purchaser's Scheme; and

         (ii)     the  Purchasers  will  procure  that  the  Purchasers  and all
                  members  of the  Purchasers'  Group  will take all  reasonable
                  steps  (including the claiming of any relevant  deduction from
                  profits and any repayment of tax and the obtaining of approval
                  of the  Purchaser's  Scheme as an Exempt  Approved  Scheme) to
                  maximise the Aggregate Tax Benefit;

         (iii)    the  Purchasers  shall within two days after the Aggregate Tax
                  Benefit has been finally determined by the Inland Revenue, pay
                  to the Seller,  by way of adjustment to the  Consideration for
                  the Shares,  an amount  equal to the  Aggregate  Tax  Benefit,
                  increased by interest at the Agreed Rate from (and  including)
                  the date of payment of the Shortfall up to (but excluding) the
                  date of payment by the Purchaser of that excess.

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                  In this subclause:

                  "Tax  Benefit"  means the aggregate of the amount by which the
                  relevant company's liability to pay corporation tax is reduced
                  and the amount of any  repayment of  corporation  tax to which
                  the  relevant  company is  entitled,  which,  in either  case,
                  arises  as a result  of the  contribution  referred  to in (i)
                  above   (including  any  such  reduction  or  right  which  is
                  attributable  to  a  surrender  by  way  of  group  relief  or
                  consortium  relief under sections 402 to 413 of the Income and
                  Corporation  Taxes Act 1988 of a loss which arises as a result
                  of the payment of the contribution); and

                  "Aggregate  Tax  Benefit"  means  the  aggregate  of  any  Tax
                  Benefits  arising to the Purchasers and the Purchasers'  Group
                  in  respect of all  accounting  periods on or before the fifth
                  anniversary of the date of Completion.

(7)      If,  for a  reason  outside  the  Seller's  control,  the  value of the
         aggregate  of the  assets  transferred  by the  Seller's  Scheme to the
         Purchaser's  Scheme  and the  assets  transferred  by the Seller to the
         Purchasers  under this clause (in the case of non-cash  assets based on
         the value of the assets transferred as at the date of transfer) exceeds
         the Transfer Amount, the Purchasers shall,  within one month of such an
         excess  having  been  transferred,  pay  to  the  Seller,  by way of an
         adjustment to the  consideration  payable for the sale of the Shares, a
         sum in cash equal to half of such  excess  adjusted  by the  Investment
         Adjustment  from (and  including) the date of transfer of the excess to
         the Purchaser's Scheme up to (but excluding) the date of payment of the
         excess by the  Purchasers  to the  Seller  provided  that the  Seller's
         Guarantor  shall have  exercised all  reasonable  endeavours to procure
         that no such excess shall arise and provided further that the amount of
         any such excess shall be available to such  Companies as are  employers
         under the Purchaser's  Scheme to fund  contributions  as employer under
         the Purchaser's Scheme notwithstanding the other provisions hereof.



12.                      PROTECTIVE COVENANTS

(1)      The Seller's  Guarantor  covenants  with the Purchasers as trustees for
         themselves  and the Companies  that it shall not and shall procure that
         no member of the Seller's Group shall:


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         (a)      for  a  period  of  12  months  from  Completion  directly  or
                  indirectly carry on any business which is competitive with any
                  of the  businesses  carried on by the  Companies at Completion
                  nor be concerned or interested in any such business; or

         (b)      for a period of 12 months from Completion induce or attempt to
                  induce any supplier of the Companies to cease to supply, or to
                  restrict or vary the terms of supply, to the Companies; or

         (c)      for a period of 12 months from Completion directly solicit the
                  employment of any present employee of the Companies; or

         (d)      at any time after Completion  disclose or divulge to any third
                  party  any  information  of a secret  or  confidential  nature
                  relating to the business or affairs of the  Companies  (except
                  as required by law or any competent  regulatory body) provided
                  that this  shall not apply to any such  information  which has
                  come into the public domain other than as a result of a breach
                  of this agreement by a member of the Seller's Group.

(2)      The  restrictions in subclause (1)(a) above shall not apply (or, as the
         case may be,  shall cease to apply)  insofar and to the extent that any
         member of the Seller's Group after Completion on bona fide arm's length
         terms  acquires  any  company or business or merges with any company or
         business and, as a result of that  transaction,  falls within the terms
         of subclause  (1)(a) above (the  "Relevant  Interest")  if turnover and
         profits  before  interest  and  taxation  attributable  to the Relevant
         Interest each constitute  less than 15 per cent. of aggregate  turnover
         and aggregate  profits before interest and taxation,  respectively,  of
         the companies and  businesses  acquired or merged with, in each case by
         reference  to the  most  recent  audited  financial  statements  of the
         relevant  companies and businesses.  If the Relevant  Interest  exceeds
         that threshold then the Seller shall if requested by a Purchaser  enter
         into bona  fide  negotiations  to sell the  Relevant  Interest  to that
         Purchaser at fair market value.

(3)      For the  purposes of subclause  (1) a member of the  Seller's  Group is
         concerned or  interested in a business if it carries it on as principal
         or agent or if:

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         (a)      it is a partner, director, employee, secondee, consultant or 
                  agent in, of or to any person who carries on the business; or

         (b)      it  has  any  direct  or  indirect   financial   interest  (as
                  shareholder  or  otherwise)  in any person who  carries on the
                  business; or

         (c)      it is a partner, director, employee,  secondee,  consultant or
                  agent in,  of or to any  person  who has a direct or  indirect
                  financial interest (as shareholder or otherwise) in any person
                  who carries on the business,

         disregarding any financial interest of a person in securities which are
         listed on the  London  Stock  Exchange  or  traded  in the  Alternative
         Investment  Market if that person and the Seller's Group are interested
         in  securities  which amount to less than five per cent.  of the issued
         securities of that class and which,  in all  circumstances,  carry less
         than five per cent.  of the  voting  rights (if any)  attaching  to the
         issued securities of that class.

(4)      Each of the  restrictions in each paragraph or subclause above shall be
         enforceable  by the  relevant  Purchaser  independently  of each of the
         others and its  validity  shall not be affected if any of the others is
         invalid;  if any of those  restrictions  is void but  would be valid if
         some part of the restrictions  were deleted the restriction in question
         shall apply with such deletion as may be necessary to make it valid.

(5)      If by  virtue  of any  provision  of  this  agreement  or of any  other
         agreement  or  arrangement  of which this  agreement  forms part,  such
         agreement  or  arrangement  is  subject  to   registration   under  the
         Restrictive  Trade  Practices  Act 1976,  none of the  parties  to such
         agreement  or  arrangement  who carries on  business  within the United
         Kingdom  shall give  effect  to, or  enforce or purport to enforce  the
         agreement or arrangement in respect of any such provision until the day
         after  particulars of the agreement or arrangement  have been furnished
         to the Director General of Fair Trading under section 24 of that Act.

13.      CHANGE OF NAME

(1)      The  Purchasers  shall  procure  that  on  or  as  soon  as  reasonably
         practicable  after Completion and in any event within ten business days
         after  Completion the names of those  Companies  which include the word
         "Graseby"  are  changed  to a name  which  does  not  include  the word
         "Graseby" or any name which is or might be confused  with that name and
         that the  Seller is  provided  with a  certified  copy of the  relevant
         special resolutions and incorporation on change of name certificates or
         the overseas equivalent.

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(2)      The Purchasers  shall be entitled to continue to use the name "Graseby"
         on all  existing  media  (including,  without  limitation,  stationery,
         brochures,   pamphlets,   catalogues,   invoices,  written  orders  and
         receipts,  building  signs  and van and  truck  livery)  of each of the
         Companies for a period of six months from Completion.

(3)      The  Purchasers  shall  further  procure that save in  accordance  with
         subclause (2) above the name  "Graseby"  will not be used by any of the
         Companies or by any member of the Purchasers'  Group and that on expiry
         of the period  referred to in  subclause  (2) above the use of the name
         "Graseby"  by each of the  Companies  or any member of the  Purchasers'
         Group will cease forthwith.

(4)      In so far as any trade or service mark  registrations  or  applications
         for  registration  are held at  Completion  by any  Company in the name
         "Graseby"  (including any trade or service mark  incorporating the name
         "Graseby")  the  Purchasers  shall  procure that any such  registration
         shall be  assigned  to the Seller  free from  encumbrances  (other than
         those existing at Completion) for a nominal  consideration  of (pound)1
         on request.

(5)      In so far as any  Intellectual  Property  Rights  owned by the  Graseby
         Group are used in the business of the Companies on or immediately prior
         to  Completion  then the Seller shall assign or procure the  assignment
         of, at the Seller's cost and expense,  all such  Intellectual  Property
         Rights as are used exclusively in the business of the Companies to such
         of the Companies as the Purchasers may nominate as soon as practicable;
         to the extent any such rights are not used  exclusively in the business
         of the Companies or pending  completion of such  assignments the Seller
         shall grant or procure that the relevant  member of its Group grants to
         the relevant Company a non-exclusive,  royalty free licence to use such
         Intellectual Property Rights as part of the relevant Company's business
         as was carried on at or  immediately  prior to  Completion  and on such
         other  terms  as shall  be  appropriate  to  protect  the  Intellectual
         Property  Rights of the Graseby  Group in those  rights  (both  parties
         acting  reasonably  and  provided no warranty  or other  obligation  in
         respect  of such  Intellectual  Property  Rights  shall be given by the
         Graseby  Group) and the  Purchasers  shall  procure  that the  relevant
         Company shall  indemnify the Seller  against all actions,  proceedings,
         costs,  damages and demands in respect of the relevant Company's use of
         any such Intellectual Property Rights under such licence. To the extent
         that any such licence or  assignment  permits the Companies to continue
         to carry out their business in substantially the same way as carried on
         prior to  Completion,  the  Seller  shall not be liable for breach of a
         Warranty  or a failure  by it to  disclose  any  Company's  use of such
         Intellectual Property Rights.

<PAGE>

            CONFIDENTIAL MATERIAL OMITTED AND FILED SEPARATELY WITH
                     THE SECURITIES AND EXCHANGE COMMISSION.
                           ASTERISKS DENOTE OMISSIONS.

(6)      In so far as any Intellectual  Property Rights are owned by any Company
         and  are  used  by  the  Seller's  Group  on or  immediately  prior  to
         Completion,  the relevant Company shall grant to the relevant member of
         the Seller's  Group a  non-exclusive,  royalty free licence to use such
         Intellectual  Property  Rights as part of the  business of the Seller's
         Group as was carried on at or  immediately  prior to Completion  and on
         such other terms as shall be  appropriate  to protect the  Intellectual
         Property  Rights of the Company in those  rights (both  parties  acting
         reasonably  and provided no warranty or other  obligation in respect of
         such  Intellectual  Property  Rights shall be given by the Company) and
         the relevant  member of the Seller's Group shall indemnify the relevant
         Company against all actions,  proceedings,  damages, claims and demands
         in respect of the relevant  member of the Seller's  Group's use of such
         Intellectual Property Rights under such licence.

(7)      Each party (and any Company)  shall be  responsible  at its own expense
         for  procuring  any right to use or  continue  using  any  Intellectual
         Property Rights belonging to any third party after  Completion.  To the
         extent that any such  licence or  assignment  permits the  Companies to
         continue to carry out their business in  substantially  the same way as
         carried  on prior to  Completion,  the  Seller  shall not be liable for
         breach of a Warranty or a failure by it to disclose any  Company's  use
         of such Intellectual Property Rights.


14A.                     GUARANTEE OF THE SELLER'S GUARANTOR

(1)      In  consideration  of the  Purchasers  and  the  Purchasers'  Guarantor
         entering into this agreement (and for other valuable  consideration the
         receipt and sufficiency of which the Seller's Guarantor  acknowledges),
         the Seller's Guarantor guarantees to each of the Purchasers the due and
         punctual  payment of all monies due by the Seller to the Purchasers and
         performance  of all  the  Seller's  other  obligations,  warranties  or
         undertakings  arising  under  this  agreement  and the Tax Deed and the
         Seller's  Guarantor  agrees to  indemnify  the  Purchasers  against all
         losses, costs,  charges,  expenses,  actions,  claims and demands which
         either  Purchaser may suffer  through or arising from any breach by the
         Seller  of its  obligations,  warranties  or  undertakings  under  this
         agreement or the Tax Deed.  The Seller's  Guarantor  shall not be under
         any  obligation  to make any  payment  to either  Purchaser  under this
         subclause  unless and until such  Purchaser has obtained a judgement in
         its favour in respect of the relevant  matter (which cannot be appealed
         against) or the Seller's Guarantor has agreed in writing to the claim.

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                     THE SECURITIES AND EXCHANGE COMMISSION.
                           ASTERISKS DENOTE OMISSIONS.

(2)      This  guarantee  shall be a  continuing  guarantee  and shall remain in
         force until all the Seller's  obligations  under this agreement and the
         Tax Deed have been performed.

(3)      The  guarantee of the Seller's  Guarantor  shall not be affected by any
         legal limitation  disability or other circumstances  (including for the
         avoidance of doubt any time or  indulgence  granted,  other  variation,
         winding  up or  cessation  of  trade)  relating  to the  Seller  or any
         irregularity,   unenforceability  or  invalidity  of  any  obligations,
         warranties or  undertakings  of the Seller under this  agreement or the
         Tax Deed.

14B.                     GUARANTEE OF THE PURCHASERS' GUARANTOR

(1)      In consideration of the Seller and the Seller's Guarantor entering into
         this agreement (and for other  valuable  consideration  the receipt and
         sufficiency  of which  the  Purchasers'  Guarantor  acknowledges),  the
         Purchasers'  Guarantor  guarantees  to the Seller the due and  punctual
         payment  of all  monies  due  by  the  Purchasers  to  the  Seller  and
         performance of all the  Purchasers'  other  obligations,  warranties or
         undertakings  arising  under  this  agreement  and the Tax Deed and the
         Purchasers'  Guarantor  agrees to  indemnify  the  Seller  against  all
         losses, costs, charges, expenses, actions, claims and demands which the
         Seller may suffer  through or arising from any breach by the Purchasers
         of their  obligations,  warranties or undertakings under this agreement
         or the Tax  Deed.  The  Purchasers'  Guarantor  shall  not be under any
         obligation  to make any  payment  to the Seller  under  this  subclause
         unless and until the Seller has  obtained a judgement  in its favour in
         respect of the relevant  matter (which  cannot be appealed  against) or
         the Purchasers' Guarantor has agreed in writing to the claim.

<PAGE>

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                     THE SECURITIES AND EXCHANGE COMMISSION.
                           ASTERISKS DENOTE OMISSIONS.

(2)      This  guarantee  shall be a  continuing  guarantee  and shall remain in
         force until all the  Purchasers'  obligations  under this agreement and
         the Tax Deed have been performed.

(3)      The guarantee of the Purchasers' Guarantor shall not be affected by any
         legal limitation  disability or other circumstances  (including for the
         avoidance of doubt any time or  indulgence  granted,  other  variation,
         winding up or cessation of trade)  relating to either of the Purchasers
         or any irregularity, unenforceability or invalidity of any obligations,
         warranties  or  undertakings  of either of the  Purchasers  under  this
         agreement or the Tax Deed.

15.       ANNOUNCEMENTS

(1)      None of the parties shall make or permit any person  connected  with it
         to make any  announcement  concerning  this  sale and  purchase  or any
         ancillary  matter  before,  on or  for a  period  of  12  months  after
         Completion  except as required by law or any competent  regulatory body
         or in  communications  in the ordinary course with its investors and/or
         any market analysts or with the written  approval of the other parties,
         such  approval  not to be  unreasonably  withheld or delayed.  No party
         shall  at any  time  make  any  announcement  regarding  this  sale and
         purchase or any ancillary  matter which might reasonably be expected to
         damage the reputation of any of the other parties in any way.

(2)      The Seller and the Purchasers  undertake that they shall not, and shall
         procure  that no  member of the  Seller's  Group or  Purchasers'  Group
         respectively  shall,  at any  time  after  the  date of this  agreement
         divulge or communicate any of the terms of this agreement to any person
         other than to its professional  advisers or with the written consent of
         the  others  or to the  extent  required  by law  or by  the  rules  or
         regulations  of the  London  Stock  Exchange  or any  other  recognised
         investment  exchange  or in  connection  with  obtaining  advice on its
         rights or  obligations  under this  agreement or enforcing or defending
         any claim in respect of the same.

16.                      NOTICES

(1)      Any notice or other  document to be served under this  agreement may be
         delivered by hand or sent by first class post or  facsimile  process to
         the party to be served at its address appearing in this agreement or at
         such other  address  as it may have  notified  to the other  parties in
         accordance with this clause.

<PAGE>

            CONFIDENTIAL MATERIAL OMITTED AND FILED SEPARATELY WITH
                     THE SECURITIES AND EXCHANGE COMMISSION.
                           ASTERISKS DENOTE OMISSIONS.

(2) Any notice or document shall be deemed to have been served:

         (a)      if delivered by hand, at the time of delivery; or

         (b)      if  posted,  at 10.00  a.m.  on the  second (or in the case of
                  international  post, the fourth) business day after it was put
                  into the post; or

         (c)      if sent by facsimile process, at the expiration of two hours 
                  after the time of despatch, if despatched before 3.00 p.m. on
                  any business day, and in any other case at 10.00 a.m. on the
                  business day following the date of despatch.

(3)      In proving  service of a notice or document it shall be  sufficient  to
         prove that delivery was made or that the envelope containing the notice
         or document was properly  addressed and posted as a prepaid first class
         letter  or that  the  facsimile  message  was  properly  addressed  and
         despatched as the case may be.

17.                      APPORTIONMENT OF FURTHER PAYMENTS

         Any  amount  to be paid by any party to the  others  under the terms of
         this  agreement  which would  constitute an increase or a reduction (as
         the  case  may  be)  in the  consideration  for  the  Shares  shall  be
         apportioned  amongst the Shares in a manner to be agreed by the parties
         to  this  agreement.  Failing  such  agreement  within  14  days of the
         relevant  payment  being  made,  the  amount of such  payment  shall be
         apportioned  in the same  proportions as the Initial  Consideration  is
         allocated between the Shares under clause 3A.

18.       GENERAL

(1)      Each of the obligations,  Warranties,  indemnities and undertakings set
         out in this agreement  which is not fully  performed at Completion will
         continue in force after Completion.

(2)      Unless  otherwise  expressly  stated all payments to be made under this
         agreement shall be made in sterling to the party to be paid as follows:

<PAGE>

            CONFIDENTIAL MATERIAL OMITTED AND FILED SEPARATELY WITH
                     THE SECURITIES AND EXCHANGE COMMISSION.
                           ASTERISKS DENOTE OMISSIONS.

         (a)      to the Seller in immediately available funds to the account of
                  the Seller at:

                  bank:               Barclays Bank Plc
                                      Broadgate Business Centre
                  sort code:          20-77-67
                  account number: 30240869

                  or such other account as the Seller may specify; and

         (b)      to the  Purchasers  in  immediately  available  funds  to such
                  account as the Purchasers may specify.

(3)      Save as  contemplated  in clause 4 and without  prejudice  to any other
         remedy  available  to any party for  breach  of this  agreement  by the
         others,  no  party  may  rescind  this  agreement  at any  time  in any
         circumstances.

(4)      The Seller or either  Purchaser  may,  without the consent of any other
         party to this  agreement,  assign to another  company  in the  Seller's
         Group or the Purchasers'  Group  respectively the benefit of all or any
         of another  party's rights under this  agreement  provided that if such
         assignee leaves the Seller's Group or Purchasers' Group respectively it
         shall immediately before it ceases to be a member of the Seller's Group
         or  Purchasers'  Group assign its rights under this agreement back to a
         member of the Seller's Group or the Purchasers'  Group, as the case may
         be,  failing which such rights shall cease to be  enforceable.  Save as
         provided in this  subclause,  none of the rights or  obligations  under
         this  agreement may be assigned or  transferred  by a party without the
         prior written consent of the Seller,  in the case of an assignment by a
         Purchaser,  or  of  the  relevant  Purchaser(s),  in  the  case  of  an
         assignment by the Seller.  The Seller's  Guarantor and the  Purchasers'
         Guarantor   agree  that  their   guarantees  in  clauses  14A  and  14B
         respectively  shall  continue  to apply in favour of any person to whom
         assignment is permitted under this subclause.

(5)      Each  party  shall  pay  the  costs  and  expenses  incurred  by  it in
         connection with the entering into and completion of this agreement.

(6)      This  agreement  may be executed in  counterparts,  each of which taken
         together shall  constitute one and the same agreement and any party may
         enter into this agreement by executing a counterpart.

<PAGE>

            CONFIDENTIAL MATERIAL OMITTED AND FILED SEPARATELY WITH
                     THE SECURITIES AND EXCHANGE COMMISSION.
                           ASTERISKS DENOTE OMISSIONS.

(7)      For a period of 12 months from the date of Completion  the Seller shall
         from time to time forthwith upon reasonable request from the Purchasers
         (at the  Seller's  expense)  do or procure the doing of all acts and/or
         execute or procure the execution of all such  documents for the purpose
         of vesting in the  Purchasers  or the relevant  Company as the relevant
         Purchaser may direct,  any member of the Graseby  Group's title to such
         assets (other than  Intellectual  Property  Rights or real property) as
         are used  exclusively  by any of the  Companies in the operation of its
         business as currently  conducted which the Purchasers  become aware are
         owned by a member of the Graseby  Group.  If any such asset (other than
         Intellectual Property Rights or real property) is also used by a member
         of the  Graseby  Group then the Seller  shall at the  Seller's  expense
         procure that the  Purchasers are granted a  non-exclusive  royalty free
         licence to use such asset.

(8)      If after the date of this  agreement  the Seller  becomes  aware of any
         real property which is owned by a member of the Graseby Group and which
         is occupied by a Company then the Seller will procure that the relevant
         member of the Graseby Group will (at the Seller's expense), transfer to
         that Company,  and the  Purchasers  will procure that such Company will
         take a  transfer  of such  property  for nil  consideration.  The terms
         governing such a transfer shall be equivalent to those terms  contained
         in an agreement  between  Goring Kerr PLC (1) and Goring Kerr Detection
         Limited  (2)  dated  11th  March,  1998  except  that  clause 4 of that
         agreement shall not be included.

19.       WHOLE AGREEMENT

(1)      This  agreement and the  documents  referred to in it contain the whole
         agreement between the parties relating to the transactions contemplated
         by this  agreement and supersede  all previous  agreements  between the
         parties relating to these transactions.

(2)      Each of the  parties  acknowledges  that in agreeing to enter into this
         agreement it has not relied on any representation, warranty, collateral
         contract or other assurance (except those set out in this agreement and
         the  documents  referred  to in it) made by or on  behalf  of any other
         party  before the  signature  of this  agreement.  Each of the  parties
         waives all rights and remedies  which,  but for this  subclause,  might
         otherwise  be  available  to it in respect of any such  representation,
         warranty, collateral contract or other assurance, provided that nothing
         in this subclause shall limit or exclude any liability for fraud.

<PAGE>

            CONFIDENTIAL MATERIAL OMITTED AND FILED SEPARATELY WITH
                     THE SECURITIES AND EXCHANGE COMMISSION.
                           ASTERISKS DENOTE OMISSIONS.

20.       GOVERNING LAW

(1) This  agreement  is governed by and shall be construed  in  accordance  with
English law.

(2)      The Purchasers and the Purchasers' Guarantor submit to the jurisdiction
         of the English  courts for all purposes  relating to this agreement and
         irrevocably  appoint  the  Purchasers'  Solicitors  as their  agent for
         service of process.


(3) AS WITNESS the hands of a duly authorised  officer of each of the parties on
the date which appears first on page 1.


SIGNED by                                   )        Alan Thomson
for and on behalf of                        )
GRASEBY LIMITED                             )



SIGNED by                                   )        D. Helm
for and on behalf of                        )
THERMO ENVIRONMENTAL                        )
INSTRUMENTS INC.                            )



SIGNED by                                   )        L. Ribich
for and on behalf of                        )
THERMO SENTRON INC.                         )



SIGNED by                                   )        Alan Thomson
for and on behalf of                        )
SMITHS INDUSTRIES plc                       )



SIGNED by                                   )        D. Helm
for and on behalf of                        )
THERMO ELECTRON                             )
CORPORATION                                 )

<PAGE>


                                                                 Exhibit 2.2


THIS AMENDMENT AGREEMENT (this "Amendment") is made on the 7th day of May, 1998


BETWEEN:


     (1) GRASEBY LIMITED  registered number 894638 whose registered office is at
765 Finchley Road, London NW11 8DS;

     (2) THERMO ENVIRONMENTAL INSTRUMENTS INC. whose principal place of business
is at 8 West Forge Parkway, Franklin, Massachusetts 02038, USA;

     (3) THERMO  SENTRON INC. whose  principal  place of business is at 501 90th
Avenue, NW, Minneapolis, Minnesota 55433, USA;

     (4) SMITHS  INDUSTRIES plc registered number 137013 whose registered office
is at 765 Finchley Road, London NW11 8DS; and

     (5) THERMO ELECTRON  CORPORATION whose principal place of business is at 81
Wyman Street, Waltham, Massachusetts 02254-9046, USA.


WHEREAS:

The parties to this Amendment  have entered into that certain  Agreement for the
sale and purchase of all the issued  share  capitals of Graseby  Allen  Limited,
Graseby  Product  Monitoring  Limited,  Goring Kerr Detection  Limited,  Graseby
Goring Kerr Inc.,  Graseby  Andersen Inc. and part of the share capital of Allen
France SA (the "Agreement").

The parties  originally  contemplated that all regulatory  approvals required by
clause 4(1) of the Agreement would be received prior to 15th May, 1998.

As of the date of this Amendment,  it appears to the parties that such approvals
will not in fact be received by 15th May, 1998.

The parties believe that it is their mutual interests to continue to pursue such
approvals.


IT IS AGREED as follows:-

                          (1)         Clause 4(3) of the Agreement is hereby 
amended and restated as follows:

         Each of the parties shall use reasonable endeavours to procure that the
         conditions  in sub clause  (1) above are  fulfilled  on or before  30th
         June,  1998 and each of the parties agrees to assist in the preparation
         of all necessary filings with,  attending  meetings with or speaking to
         (if necessary) the regulatory authorities referred to in sub clause (1)
         above.

(2) Except as otherwise  provided  herein,  the  Agreement  shall remain in full
force and effect.

(3)      This  Agreement  may be executed in  counterparts,  each of which taken
         together shall  constitute one and the same agreement and any party may
         enter into this Agreement by executing a counterpart.

(4) This  Amendment  is governed by and shall be construed  in  accordance  with
English law.


AS WITNESS the hands of a duly authorised  officer of each of the parties on the
date which appears first above.


SIGNED by                  )                 Alan Thomson
 ........................   )
for and on behalf of       )
GRASEBY LIMITED            )


SIGNED by                  )                 Melissa F. Riordan
for and on behalf of       )
THERMO ENVIRONMENTAL       )
INSTRUMENTS INC.           )



SIGNED by                  )                 Melissa F. Riordan
 ........................   )
for and on behalf of       )
THERMO SENTRON INC.        )



SIGNED by                  )                 Alan Thomson
 ........................   )
for and on behalf of       )
SMITHS INDUSTRIES plc      )


SIGNED by                  )                 Melissa F. Riordan
 .....................      )
for and on behalf of       )
THERMO ELECTRON            )
CORPORATION                )



<PAGE>



                                                                 Exhibit 2.3




                               DATED 9 June, 1998





                                 GRASEBY LIMITED
                      THERMO ENVIRONMENTAL INSTRUMENTS INC.
                               THERMO SENTRON INC.
                              SMITHS INDUSTRIES plc

                                       and

                           THERMO ELECTRON CORPORATION






                  --------------------------------------------

                                    AGREEMENT

                     to further amend the sale and purchase
                            agreement entered into by
                             the above parties dated
                                13th March, 1998
                (as amended by an agreement dated 7th May, 1998)
                  --------------------------------------------









<PAGE>



THIS AGREEMENT is made on 9th June, 1998 BETWEEN:

     (1) GRASEBY LIMITED  registered number 894638 whose registered office is at
765 Finchley Road, London NW11 8DS (the "Seller");

     (2) THERMO ENVIRONMENTAL INSTRUMENTS INC. whose principal place of business
is at 8 West Forge Parkway, franklin, Massachusetts 02038, USA 
("Environmental");

     (3) THERMO  SENTRON INC. whose  principal  place of business is at 501 90th
Avenue, NW, Minneapolis, Minnesota 55433, USA ("Sentron");

     (4) SMITHS  INDUSTRIES plc registered number 137013 whose registered office
is at 765 Finchley Road,
         London, NW11 8DS (the "Seller's Guarantor"); and

     (5) THERMO ELECTRON CORPORATION whose principal place of business is at 81
         Wyman Street, Waltham,  Massachusetts 02254-9046, USA (the "Purchasers'
         Guarantor").

WHEREAS:

(A)      The above  parties  entered into a sale and purchase  agreement on 13th
         March, 1998 (the "Original  Agreement") relating to the sale of all the
         issued  share  capitals  of  Allen,  Product  Monitoring,  Goring  Kerr
         Detection,  Goring  Kerr and  Andersen  Inc.  and the  shares  in Allen
         France.  In order to obtain US  Hart-Scott-  Rodino  clearance  for the
         transactions  contemplated in the Original  Agreement,  the parties now
         wish to  exclude  Graseby  Specac  Limited  and the US Specac  business
         carried  on  by  Andersen  Inc.  (together,  "Specac")  from  the  sale
         contemplated in the Original Agreement.

(B)      The Original  Agreement was amended by an agreement between the parties
         dated  7th  May,  1998 to  extend  the  date  for  satisfaction  of the
         condition precedent in clause 4(1)(a) of the Original Agreement.

(C)      Accordingly the parties have agreed to amend the Original Agreement and
         to certain other matters, as set out in this agreement.

IT IS AGREED as follows:

1.       INTERPRETATION

         All  words and  expressions  defined  in or  pursuant  to the  Original
         Agreement shall have the same meaning in this  agreement,  except where
         amended by this agreement.


2.       CHANGES TO ORIGINAL AGREEMENT

     (1) Save as modified by this agreement,  the Original Agreement (as amended
on 7th May, 1998) shall continue to have effect.

     (2) The Original Agreement shall be deemed to be amended,  with effect from
the date of this agreement, as follows:

         (a)      recital (I) shall be deleted and replaced by the following:

                  "(I)     Graseby  Andersen Limited  ("Andersen  Limited") is a
                           private company  limited by shares short  particulars
                           of which are set out in Part F of  Schedule  1 having
                           an authorised  capital of (pound)100 divided into 100
                           ordinary shares of (pound)1 each of which 2 have been
                           issued (the "Andersen Limited Shares")";

         (b)      recital (J) shall be amended by inserting  "Andersen  Limited"
                  after "Goring Kerr " on the second line;

         (c)      recital (K) shall be amended by inserting ", Andersen  Limited
                  Shares" after "Goring Kerr Shares" on the second line;

         (d)      clause 1(1) shall be amended by:

     (1) changing the figure referred to in the definition of "Companies' Loans"
to (pound)6,359,829; and

     (2) changing the figure  referred to in the definition of "Seller's  Loans"
to
                           (pound)2,280,148;

         (e) clause 1(5) shall be amended by deleting  "Graseby  Specac  Limited
and " from paragraph (f);

     (f) clause  2(1)(b)  shall be amended by adding "and the  Andersen  Limited
Shares" after "Andersen Inc. Shares";

         (g)      clause 3A shall be amended by:

     (1)  deleting  "(pound)35,260,319"  on the first line and  replacing  it by
"(pound)35,460,319";

     (2) delete "and" at the end of clause 3A(e) and insert ";and" at the end of
clause 3A(f); and

     (3) adding a new  paragraph (g) as follows:  "(g) for the Andersen  Limited
Shares, the sum of (pound)200,000";

         (h)      clause 3B(1) shall be amended by replacing "(pound)11,244,000"
                  on the first and fourth lines by "(pound)9,546,000";

         (i)      Clause  8(2)(a)(i)  shall be  amended by adding at the end the
                  words "and a duly executed  declaration  of trust in favour of
                  Environmental in respect of the Andersen Limited Shares";

         (j)      clause  8(2)(a)(ii)  shall be amended by adding after "Product
                  Monitoring Shares" the words ", Andersen Limited Shares";

         (k)      clause  8(2)(a)(v)  shall be  amended by adding at the end the
                  words "not already in the possession of the Companies";

         (l)      Part G of Schedule 2 shall be deleted;

         (m)      Part H of  Schedule  2  shall  be  redesignated  as  Part F of
                  Schedule 1 and opposite the word  "Shareholder"  in that Part,
                  the  word  "Graseby  Specac  Limited"  shall  be  deleted  and
                  replaced by "Graseby Limited as to the beneficial interest and
                  Graseby Specac Limited as to the legal interest"; and

         (n) Part B of Schedule 3 shall be amended by:

     (1) deleting the reference  "(Shares with Graseby Specac Limited)" from the
end of entry for Legal Owner for the Atlanta property (number (13)) on page 43;

     (2) deleting the entry for the Orpington  Property (number (19)) on page 45
and replacing it as follows:

     "(19)  Description:  Part  Ground  Floor and Part Top Floor,  Cray  Avenue,
Orpington (Title No: SGL579547)

     Date of and parties of Graseby  agreement  for lease:  June,  1998  between
Graseby Limited (1) and Andersen Limited (2)

     Legal and Beneficial  owner of interest under agreement for lease:  Graseby
Andersen Limited

                          Term: a maximum of 6 months from Completion



                                    Present rent:             (pound)2,250 pcm

                                    Next rent review:Not applicable

                                    Present use:              Factory/offices";

     (3) deleting all reference to the Newmarket  property at entry (20) on page
45.

(3)      Any references in the Original  Agreement to "this  agreement" shall be
         construed as  references  to the  Original  Agreement as amended by the
         amendment agreement dated 7th May, 1998 and by this agreement.

(4)      The Purchasers  acknowledge that the Seller has taken or procured to be
         taken the following steps to exclude Specac from the sale  contemplated
         by the Original Agreement:

         (a)      by an agreement  dated 8th June,  1998  Andersen Inc. sold the
                  beneficial  interest  in all  its  shares  in  Graseby  Specac
                  Limited  to  the  Seller  for   (pound)5,984,911  to  be  left
                  outstanding on inter-company  loan account and  simultaneously
                  declared  that it held the legal  interest  in such  shares on
                  trust for the Seller;

         (b)      by an agreement  dated 9th June,  1998 Graseby  Specac Limited
                  sold the beneficial interest in the Andersen Limited Shares to
                  the  Seller  for  (pound)200,000  to be  left  outstanding  on
                  inter-company loan account and simultaneously declared that it
                  held the  legal  interest  in such  shares  on  trust  for the
                  Seller; and

         (c)      by an agreement dated 9th June, 1998 Andersen Inc. sold its US
                  Specac business to Specac Inc. (a member of the Graseby Group)
                  for (pound)79,000 to be left outstanding on inter-company loan
                  account.

(5)      The  Purchasers  acknowledge  their consent (for the purposes of clause
         5(1) of the Original  Agreement) to the taking of the steps referred to
         in  subclause  (4) and that  copies of the  agreements  referred  to in
         subclause (4) have been disclosed to them by the Seller. The Purchasers
         further  agree that they shall not be able to make any claim  under the
         Warranties or other terms of the Original Agreement (if applicable) due
         to the transactions contemplated in those agreements occurring.

(6)      The parties  acknowledge that the condition precedent in clause 4(1)(b)
         of the Original Agreement has been satisfied and that Completion of the
         Original  Agreement  shall take place on Friday 12th June,  1998 if (i)
         the  US  Federal  Trade  Commission  or the US  Department  of  Justice
         provides unconditional clearance in respect of the sale contemplated in
         the  Original  Agreement  as  amended  by this  agreement  or (ii)  all
         appropriate  waiting  periods  and any other  time  periods  (including
         extensions   thereto)   under   the  US   Hart-Scott-Rodino   Antitrust
         Improvements  Act 1976 (as amended) and the regulations made thereunder
         have  expired,  lapsed  or  been  terminated  in  respect  of the  sale
         contemplated in the Original Agreement as amended by this agreement, in
         each case on or before  Thursday 11th June, 1998 ((i) and (ii) together
         "Clearance")  . If  Clearance  is not  received  on or before such time
         Completion  shall take place within four  business  days of the date of
         actual Clearance.

(7)      At  Completion  the Tax Deed to be  entered  into by the Seller and the
         Purchasers shall,  notwithstanding  anything  contained in the Original
         Agreement,  be in the form appended to this agreement,  instead of that
         agreed by the parties on 13th March, 1998.

3.       NON-OBJECTION

         The  Purchasers  undertake  to the  Seller  not to submit to the United
         States Department of Justice, the European Commission or any applicable
         national competition or regulatory authority any complaint or objection
         to the sale of Specac by the Seller,  irrespective  of the  identity of
         the  purchaser  of  Specac,  provided  that this will not  prevent  the
         Purchasers  complying with any obligations with regard to the provision
         of  information  or  otherwise  under the  Hart-Scott-Rodino  Antitrust
         Improvements  Act of 1976,  the EC Merger  Control  Regulation,  or any
         other  applicable  law or  regulation.  When  asked by any of the above
         regulatory  authorities  to  comply  with any  obligations  to  provide
         information, the Purchasers shall inform the Seller of this fact unless
         this  constitutes  a  breach  of  the  Purchasers'   obligations  under
         applicable law or regulations.

4.       INTERIM TRANSITIONAL ARRANGEMENTS

(1)      The Purchasers shall procure that  post-Completion  Andersen Inc. shall
         provide  certain  limited  services to Graseby  Specac  Limited  and/or
         Specac Inc. and the Seller shall  procure that Graseby  Specac  Limited
         shall provide certain limited services to Graseby Andersen Limited, all
         such services to be supplied as a temporary  measure in accordance with
         the  principal  terms  and  conditions  set out in  Schedule  1 to this
         agreement.

(2)      If any  obligation or liability  shall arise on Andersen Inc. to make a
         payment  of US  Taxation  to a  Taxation  Authority  in respect or as a
         result of any  transfer  or sale of all the  issued  share  capital  of
         Graseby  Specac  Limited  from  Andersen  Inc.  to  the  Seller,   such
         obligation  or  liability  shall be shared  as to the first  US$500,000
         equally  between the  Purchasers  on the one hand and the Seller on the
         other  hand  and  thereafter  (in  the  event  the  liability   exceeds
         US$500,000)  shall be borne by the Seller alone.  Any payment due under
         this sub-clause  shall be made within 7 days of the amount becoming due
         to a  Taxation  Authority  and  shall  operate  to reduce  the  Initial
         Consideration  for the  Andersen  Inc.  Shares  by the  amount  of such
         payment.

(3)      For  the  purposes  of  this  clause  the  expressions  "Taxation"  and
         "Taxation Authority" shall have the same meaning as they bear under the
         Tax Deed.

5.       EMPLOYEES

         The Seller and  Environmental  agree to use their  best  endeavours  to
procure that:

         (a)      Graseby Specac Limited, Andersen Inc. and Specac Inc. agree
                  with M Cruickshank and A Bibby that:

                  (i)      to the  extent  that  they are  employed  by  Graseby
                           Specac  Limited and  seconded to Andersen  Inc.,  the
                           terms  and  conditions  of  their   secondment   will
                           transfer  to Specac Inc on broadly  equivalent  terms
                           and  conditions as those enjoyed by them  immediately
                           prior to Completion; and

                  (ii)     to the  extent  that they are  employed  by  Andersen
                           Inc.,  all necessary  steps will be taken to transfer
                           their employment to Specac Inc. on broadly equivalent
                           terms  and   conditions  as  those  enjoyed  by  them
                           immediately prior to Completion; and

     (b) the employment of P Galloway is transferred at Completion from Andersen
Inc. to Specac Inc. on terms and conditions  overall equivalent to those enjoyed
by her immediately prior to Completion.

6.        CONFIDENTIAL INFORMATION

(1)      "Information"  means  information of whatever nature relating to Specac
         supplied to the  Purchasers,  Purchasers'  Guarantor or the Purchaser's
         advisers by or on behalf of the Seller in writing,  orally or otherwise
         and includes any information  obtained by the  Purchasers,  Purchasers'
         Guarantor or the Purchasers'  advisers,  in writing or orally,  through
         discussions with the management,  employees and advisers of the Seller,
         together  with any reports,  analyses,  compilations,  studies or other
         documents  prepared by the  Purchasers or on their behalf which contain
         or otherwise reflect such information.

(2)      The  Purchasers  undertake to the Seller to keep strictly  confidential
         all  Information  relating to Specac.  The Purchasers  will not use the
         Information in any way that could be directly or indirectly detrimental
         to the Seller or Specac or so as to procure  any  commercial  advantage
         over the Seller or the Specac business.

(3)      The Purchasers  shall use all their  reasonable  endeavours to promptly
         return to the Seller or  destroy  all  copies of  Information  in their
         possession or control relating to Specac without keeping any copies and
         deliver to the Seller or destroy all notes (and any copies) prepared by
         them (and by any person to whom  disclosure  has been made) and use all
         their reasonable  endeavours to destroy or expunge all Information from
         any computer, word processor or other device containing it.

(4) The Purchasers further acknowledge and confirm to the Seller that:

         (a)      remedies at law may be inadequate to protect  against a breach
                  of this clause and hereby  agree in  advance,  in the event of
                  any such breach on their part,  not to oppose the  granting of
                  injunctive  relief,  specific  performance or other  equitable
                  relief in favour of the Seller without proof of actual damage;

         (b)      no  failure  or  delay  in  exercising  any  right,  power  or
                  privilege  under this clause  will  operate as a waiver of it,
                  nor will any single or partial  exercise  of it  preclude  any
                  further  exercise  or the  exercise  of any  right,  power  or
                  privilege  under this clause or otherwise.  No modification to
                  this clause or any waiver  granted by the Seller in respect of
                  any action taken by the  Purchasers or their advisers shall be
                  effective unless agreed in writing by the Seller; and

         (3)      the  provisions of this clause shall be severable in the event
                  that  any of the  provisions  hereof  are  held by a court  of
                  competent  jurisdiction  to  be  invalid,  void  or  otherwise
                  unenforceable,  and  the  remaining  provisions  shall  remain
                  enforceable to the fullest extent permitted by law.

7A.                      GUARANTEE OF THE SELLER'S GUARANTOR

         The  Seller's  Guarantor  confirms to each of the  Purchasers  that the
         guarantee  given by the  Seller's  Guarantor  under  clause  14A of the
         Original Agreement shall remain in effect  notwithstanding  the changes
         made by the agreement dated 7th May, 1998 and this agreement.

7B.                      GUARANTEE OF THE PURCHASERS' GUARANTOR

         The  Purchasers'  Guarantor  confirms to the Seller that the  guarantee
         given by the  Purchasers'  Guarantor  under  clause 14B of the Original
         Agreement  shall remain in effect  notwithstanding  the changes made by
         the agreement dated 7th May, 1998 and this agreement.

8.                       SEC FINANCIAL STATEMENTS

         The Seller  acknowledges that the Purchasers will be obliged to prepare
         and file  with the U.S.  Securities  and  Exchange  Commission  certain
         financial  statements ("SEC Financial  Statements") with respect to one
         or more of the  Companies,  and that, in  accordance  with UK generally
         accepted  accounting  principles  as  applied  by  the  Seller  to  the
         Companies,  not all of the  information  necessary  to prepare such SEC
         Financial   Statements  in  accordance   with  US  generally   accepted
         accounting  principles  is  contained  in the books and  records of the
         Companies.  Accordingly,  the Seller agrees (i) to co-operate  with the
         Purchasers  and to provide the  Purchasers  with access to the Seller's
         own books and records;  and (ii) to use its  reasonable  endeavours  to
         procure that the Seller's  Accountants  co-operate with the Purchasers,
         including providing access to the Seller's Accountants' work papers, in
         each such case, to the extent  reasonably  necessary  (and only to such
         extent) for the  Purchasers to prepare such SEC  Financial  Statements.
         Such  co-operation  and access shall be provided to the  Purchasers  or
         their accountants during normal working hours at the Seller's principal
         places of business  or at any  location  (including  the offices of the
         Seller's Accountants) where such books and records are maintained.  The
         Purchasers may reasonably  require that the Seller (or they  themselves
         with the prior consent of the Seller) make copies of any such books and
         records  at the  Purchasers'  cost;  provided,  however,  that any such
         copying  shall  be  done  in  such  manner  so as not  to  unreasonably
         interfere  with  the  normal  conduct  of the  Seller's  business.  The
         Purchasers  undertake to the Seller (save as required by applicable law
         or  regulation  and  provided  the  same  is not in the  public  domain
         otherwise than as a result of a breach of this clause) to keep strictly
         confidential all information  obtained  pursuant to this clause and not
         to use any such  information  in any way  that  could  be  directly  or
         indirectly  detrimental to the Seller or Specac or so as to procure any
         commercial  advantage  over the  Seller  or the  Specac  business.  The
         Purchasers further agree that the provisions of clause 6(4) shall apply
         mutatis mutandis to this clause.

9.        GENERAL

(1)      This  agreement  may be executed in  counterparts,  each of which taken
         together shall  constitute one and the same agreement and any party may
         enter into this agreement by executing a counterpart.

(2)      In the event of any  inconsistency  between  the terms of the  Original
         Agreement and the terms of this agreement,  the terms of this agreement
         shall prevail.

(3)      The  provisions  of  clause  15,  16,  18,  19 and  20 of the  Original
         Agreement  shall  apply  to  this  agreement  mutatis  mutandis  as  if
         references in the Original Agreement were references to this agreement.

(4)      Clause 2(2)(i) contemplates that the Purchasers will be provided with a
         duly executed  stock  transfer form in respect of the Andersen  Limited
         Shares (the "Form"). The Seller shall use all reasonable  endeavours to
         procure  that  the  Purchasers  are  provided  with the Form as soon as
         possible after Completion but the Seller undertakes to provide the Form
         to the  Purchasers  within 6 months of Completion in any event.  If the
         Purchasers  become liable to pay a penalty or fine or similar charge to
         the Inland Revenue as a result of their not having been provided within
         28 days of  Completion  with the Form the Seller  shall  reimburse  the
         Purchasers  the same  amount as such  penalty,  fine or similar  charge
         (less the amount of stamp duty comprised therein).


<PAGE>


AS WITNESS the hands of a duly authorised  officer of each of the parties on the
date which appears first on page 1.



SIGNED by                                   )        Alan Thomson
for and on behalf of                        )
GRASEBY LIMITED   )




SIGNED by                                   )        L. J. Ribich
for and on behalf of                        )
THERMO ENVIRONMENTAL                        )
INSTRUMENTS INC.                            )




SIGNED by                                   )        L. J. Ribich
for and on behalf of                        )
THERMO SENTRON INC.                         )




SIGNED by                                   )        Alan Thomson
for and on behalf of                        )
SMITHS INDUSTRIES plc                       )




SIGNED by                                   )        L. J. Ribich
for and on behalf of                        )
THERMO ELECTRON                             )
CORPORATION                                 )



<PAGE>





                                                                     Exhibit 10


                 THE SECURITIES REPRESENTED HEREBY HAVE NOT BEEN
                 REGISTERED UNDER THE SECURITIES ACT OF 1933, AS
                 AMENDED (THE "ACT"). THESE SECURITIES HAVE BEEN
                 ACQUIRED FOR INVESTMENT, AND NOT WITH A VIEW TO
              DISTRIBUTION OR RESALE, AND MAY NOT BE SOLD, PLEDGED,
              MORTGAGED, HYPOTHECATED OR OTHERWISE TRANSFERRED (1)
              WITHOUT AN EFFECTIVE REGISTRATION STATEMENT UNDER THE
                 ACT COVERING THESE SECURITIES OR (2) UNLESS AN
                    EXEMPTION FROM REGISTRATION IS AVAILABLE.



                              THERMO SENTRON INC.

                      Promissory Note Due December 15, 1998
                             Minneapolis, Minnesota

June 12, 1998


         For value received,  Thermo Sentron Inc., a Delaware  corporation  (the
"Company"),  hereby promises to pay to Thermo Electron Corporation  (hereinafter
referred to as the  "Payee"),  or registered  assigns,  on December 15, 1998, as
described   below,   the   principal   sum   of   twenty-one   million   dollars
($21,000,000.00)  or such part thereof as then remains  unpaid,  to pay interest
from the date hereof on the whole amount of said  principal sum  remaining  from
time to time  unpaid  at a rate per  annum  equal to the rate of the  Commercial
Paper Composite Rate for 90-day  maturities as reported by Merrill Lynch Capital
Markets,  as an average of the last five business  days of the Company's  latest
fiscal quarter then ended, plus twenty-five (25) basis points,  which rate shall
be adjusted on the first  business day of each fiscal quarter of the Company and
shall be in effect for the entirety of such fiscal quarter,  such interest to be
payable in arrears on the first day of each fiscal quarter of the Company during
the term set  forth  herein,  until the whole  amount  of the  principal  hereof
remaining  unpaid  shall  become due and  payable,  and to pay  interest  on all
overdue principal and interest at a rate per annum equal to the rate of interest
announced  from time to time by  BankBoston,  N.A. at its head office in Boston,
Massachusetts  as its "base  rate " plus one  percent  (1%).  Principal  and all
accrued but unpaid interest shall be repaid on December 15, 1998.  Principal and
interest  shall be payable in lawful money of the United  States of America,  in
immediately  available  funds,  at the principal  office of the Payee or at such
other place as the legal  holder may  designate  from time to time in writing to
the Company. Interest shall be computed on an actual 360-day basis.

         This Note may be prepaid at any time or from time to time,  in whole or
in part, without any premium or penalty.  All prepayments shall be applied first
to accrued interest and then to principal.

         The then unpaid principal amount of, and interest  outstanding on, this
Note shall be and become  immediately  due and payable without notice or demand,
at the option of the holder hereof,  upon the occurrence of any of the following
events:

     (a) the failure of the Company to pay any amount due  hereunder  within ten
(10) days of the date when due;

                  (b)  any   representation,   warranty  or  statement  made  or
furnished  to the  Payee by the  Company  in  connection  with  this Note or the
transaction from which it arises shall prove to have been false or misleading in
any material respect as of the date when made or furnished;

                  (c) the failure of the Company to pay its debts as they become
due, the insolvency of the Company,  the filing by or against the Company of any
petition under the U.S.  Bankruptcy Code (or the filing of any similar  petition
under the insolvency law of any  jurisdiction),  or the making by the Company of
an assignment or trust mortgage for the benefit of creditors or the  appointment
of a receiver,  custodian or similar agent with respect to, or the taking by any
such person of possession of, any property of the Company;

                  (d) the sale by the Company of all or substantially all of
its assets;

                  (e) the merger or  consolidation  of the Company  with or into
any other corporation in a transaction in which the Company is not the surviving
entity;

                  (f) the issuance of any writ of attachment, by trustee process
or otherwise,  or any restraining  order or injunction not removed,  repealed or
dismissed  within thirty (30) days of issuance,  against or affecting the person
or property of the Company or any  liability or obligation of the Company to the
holder hereof; and

                  (g) the suspension of the transaction of the usual business of
the Company.

         Upon surrender of this Note for transfer or exchange, a new Note or new
Notes of the same tenor  dated the date to which  interest  has been paid on the
surrendered  Note and in an  aggregate  principal  amount  equal  to the  unpaid
principal amount of the Note so surrendered will be issued to, and registered in
the name of, the transferee or transferees.  The Company may treat the person in
whose  name this Note is  registered  as the owner  hereof  for the  purpose  of
receiving payment and for all other purposes.

         In case any payment herein provided for shall not be paid when due, the
Company further promises to pay all cost of collection, including all reasonable
attorneys' fees.

         No delay or omission on the part of the Payee in  exercising  any right
hereunder  shall  operate as a waiver of such right or of any other right of the
Payee,  nor shall any delay,  omission or waiver on any one occasion be deemed a
bar to or waiver  of the same or any other  right on any  future  occasion.  The
Company hereby waives presentment, demand, notice of prepayment, protest and all
other  demands  and  notices  in  connection  with  the  delivery,   acceptance,
performance, default or enforcement of this Note. The undersigned hereby assents
to any  indulgence  and any  extension  of time for payment of any  indebtedness
evidenced hereby granted or permitted by the Payee.

         This Note shall be governed by and  construed in accordance  with,  the
laws of the Commonwealth of Massachusetts  and shall have the effect of a sealed
instrument.


                                              THERMO SENTRON INC.



                                              By:/s/ Lewis J. Ribich
                                              Title:   President



[Corporate Seal]

Attest:


/s/ Carl F. Barnes
[{"type": "8-K", "sequence": "1", "description": "FORM 8K WITH EXHIBITS ATTACHED", "secsgml_size_bytes": 150800}]
{"company-data": {"conformed-name": "THERMO SENTRON INC", "cik": "0001007022", "assigned-sic": "3560", "irs-number": "411827303", "state-of-incorporation": "DE", "fiscal-year-end": "1231"}, "filing-values": {"form-type": "8-K", "act": "34", "file-number": "001-14254", "film-number": "98653946"}, "business-address": {"street1": "501 90TH AVE NW", "city": "MINNEAPOLIS", "state": "MN", "zip": "55433", "phone": "6126221000"}, "mail-address": {"street1": "501 90TH AVENUE NW", "city": "MINNEAPOLIS", "state": "MN", "zip": "55433"}}
SECURITIES AND EXCHANGE COMMISSION

                             Washington, D.C. 20549

                   -------------------------------------------

                                    FORM 8-K

                                 CURRENT REPORT

                       Pursuant to Section 13 or 15(d) of
                       the Securities Exchange Act of 1934

                                 Date of Report
                             (Date of earliest event
                                   reported):

                                  June 12, 1998

                    ----------------------------------------

                               THERMO SENTRON INC.
             (Exact name of Registrant as specified in its charter)

Delaware                        1-14254                      41-1827303
(State or other               (Commission                   (I.R.S. Employer
jurisdiction of               File Number)                Identification Number)
incorporation or
organization)

501 90th Avenue N.W.
Minneapolis, Minnesota                                              55433
(Address of principal executive offices)                          (Zip Code)

                                 (781) 622-1000
                         (Registrant's telephone number
                              including area code)
Item 2.  Acquisition or Disposition of Assets

        On June 12, 1998, Thermo Sentron Inc. (the "Company") acquired the three
businesses  that  constitute  the  Graseby  product-monitoring  group  ("Graseby
Product  Monitoring")  from  Graseby  Limited  (the  "Seller").  The  businesses
acquired   design,   manufacture  and  distribute   specialized   packaged-goods
equipment,  including  checkweighers  and metal detectors,  primarily for use by
food producers and  pharmaceutical  companies.  Graseby  Product  Monitoring had
revenues of approximately $46 million for the year ended December 31, 1997.

         The  acquisition was made pursuant to an Agreement dated March 13, 1998
(as  amended,  the  "Agreement"),  between  the  Seller,  the Company and Thermo
Environmental  Instruments  Inc.,  which  acquired  a separate  business  of the
Seller.  Smiths  Industries  plc, the parent  company of the Seller,  and Thermo
Electron  Corporation,  the indirect parent company of the Company and of Thermo
Environmental  Instruments  Inc.,  guaranteed the respective  obligations of the
parties.

         The purchase price of Graseby Product  Monitoring was approximately $43
million,  net of cash acquired.  The purchase price is subject to a post-closing
adjustment equal to the amount by which the net operating assets (excluding cash
balances and certain other identified items) of Graseby Product Monitoring as of
the closing date are greater or less than,  as the case may be,  certain  target
amounts set forth in the Agreement.

         The consideration  paid for Graseby Product Monitoring was based on the
Company's determination of the fair market value of Graseby Product Monitoring's
business,  and  the  terms  of the  Agreement  were  determined  by  arms-length
negotiation among the parties.

         To finance the acquisition,  the Company utilized  approximately  $34.6
million of available  cash and  approximately  $8.6 million of  borrowings  from
Thermo  Electron.  The  indebtedness to Thermo Electron bears interest at a rate
equal to the 90-day Commercial Paper Composite Rate plus 25 basis points, set at
the beginning of each quarter, and is due December 15, 1998.

         The  Company  has no  present  intention  to use the  assets of Graseby
Product Monitoring for purposes materially different from the purposes for which
such assets were used prior to the acquisition. However, the Company will review
such  business's  assets,  corporate  structure,   capitalization,   operations,
properties,  policies,  managements  and personnel and, upon  completion of this
review,  may develop  additional or  alternative  plans or proposals,  including
mergers,   transfers  of  a  material  amount  of  assets  or  other  additional
transactions or changes relating to such business.

     Item 7.  Financial  Statements,  Pro  Forma  Combined  Condensed  Financial
Information and Exhibits

             (a)         Financial Statements of Business Acquired:  Information
                         meeting  the  requirements  of this  Item  7(a) will be
                         filed by amendment  within the time period permitted by
                         Item 7(a)(4) of Form 8-K.

             (b)         Pro Forma  Combined  Condensed  Financial  Information:
                         Information  meeting the requirements of this Item 7(b)
                         will be  filed by  amendment  within  the  time  period
                         permitted by Item 7(a)(4) of Form 8-K.

             (c)          Exhibits

                           2.1*     Agreement  dated March 13, 1998 for the sale
                                    and  purchase  of all of  the  issued  share
                                    capitals of Graseby Allen  Limited,  Graseby
                                    Product  Monitoring  Limited,   Goring  Kerr
                                    Detection Limited, Graseby Goring Kerr Inc.,
                                    Graseby  Andersen Inc. and part of the share
                                    capital  of  Allen  France   S.A.,   between
                                    Graseby   Limited,    Thermo   Environmental
                                    Instruments   Inc.,   Thermo  Sentron  Inc.,
                                    Smiths  Industries  plc and Thermo  Electron
                                    Corporation.  Pursuant to Item  601(b)(2) of
                                    regulation  S-K,  schedules  and exhibits to
                                    this  Agreement   have  been  omitted.   The
                                    Company   hereby   undertakes   to   furnish
                                    supplementally  a copy of such schedules and
                                    exhibits to the Commission upon request.

                           2.2     Amendment  Agreement dated May 7, 1998  
                                   between Graseby Limited,  Thermo 
                                   Environmental Instruments  Inc., Thermo
                                   Sentron Inc., Smiths Industries plc and 
                                   Thermo Electron Corporation.

                           2.3      Agreement,  dated June 9,  1998,  to further
                                    amend the sale and purchase  agreement dated
                                    March  13,  1998  between  Graseby  Limited,
                                    Thermo   Environmental   Instruments   Inc.,
                                    Thermo Sentron Inc.,  Smiths  Industries plc
                                    and Thermo Electron Corporation. Pursuant to
                                    Item 601(b)(2) of regulation S-K,  schedules
                                    and  exhibits  to this  Amendment  Agreement
                                    have  been  omitted.   The  Company   hereby
                                    undertakes to furnish  supplementally a copy
                                    of  such   schedules  and  exhibits  to  the
                                    Commission upon request.

                           10.      $21.0 Million Promissory Note due December 
                                    15, 1998, payable to Thermo
                                    Electron Corporation.

      *          Confidential  treatment requested as to certain portions of the
                 document, which portions have been omitted and filed separately
                 with the Securities and Exchange Commission.
SIGNATURES

         Pursuant to the  requirements  of the Securities  Exchange Act of 1934,
the  Registrant  has duly  caused  this report to be signed on its behalf by the
undersigned thereunto duly authorized, on this 24th day of June, 1998.

                                                  THERMO SENTRON INC.

                                                  By: /s/ Melissa F. Riordan
                                                       Melissa F. Riordan
                                                       Treasurer
CONFIDENTIAL MATERIAL OMITTED AND FILED SEPARATELY WITH
                     THE SECURITIES AND EXCHANGE COMMISSION.
                           ASTERISKS DENOTE OMISSIONS.

                                                                    Exhibit 2.1

                             DATED 13th MARCH, 1998

                                 GRASEBY LIMITED
                      THERMO ENVIRONMENTAL INSTRUMENTS INC.
                               THERMO SENTRON INC.
                              SMITHS INDUSTRIES plc

                                       and

                           THERMO ELECTRON CORPORATION

                         ------------------------------

                                    AGREEMENT

                          for the sale and purchase of
                        all the issued share capitals of
                              GRASEBY ALLEN LIMITED
                       GRASEBY PRODUCT MONITORING LIMITED
                          GORING KERR DETECTION LIMITED
                             GRASEBY GORING KERR INC
                              GRASEBY ANDERSEN INC
                                       and
                          Part of the share capital of
                                 ALLEN FRANCE SA
                         ------------------------------
CONFIDENTIAL MATERIAL OMITTED AND FILED SEPARATELY WITH
                     THE SECURITIES AND EXCHANGE COMMISSION.
                           ASTERISKS DENOTE OMISSIONS.

                                    CONTENTS

Clause                                                                Page

1.       Interpretation.................................................3
2.       Sale and Purchase of the Shares................................6
3A.      Initial Consideration..........................................7
3B.      Consideration Adjustment.......................................7
3C.      Indemnity......................................................11
3D.      **** Claim.....................................................11
4.       Conditions Precedent...........................................15
5.       Covenants up to Completion.....................................15
6.       Warranties.....................................................18
7.       Tax Deed.......................................................22
8.       Completion.....................................................22
9.       Loan Accounts and Settlement of Cash Balances..................24
10.      Guarantees.....................................................25
11.      Pensions.......................................................25
12.      Protective Covenants...........................................29
13.      Change of Name.................................................31
14A.     Guarantee of the Seller's Guarantor............................33
14B.     Guarantee of the Purchasers' Guarantor.........................34
15.      Announcements..................................................35
16.      Notices........................................................35
17.      Apportionment of Further Payments..............................36
18.      General........................................................36
19.      Whole Agreement................................................38
20.      Governing Law..................................................39

Schedules

1.       Particulars of the Companies.....................................
2.       Particulars of Subsidiary Companies..............................
3.       Properties.......................................................
4.       Pensions.........................................................
5.       Agreed Accounting Principles.....................................
6.       Warranties.......................................................

Agreed Form Documents

1.     Accountants' Reports
2.     Statement of Companies' Loans
3.     Information Memoranda
4.     Statement of Seller's Loans
5.     Disclosure Letter
6.     Tax Deed
7.      Severance Costs
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                           ASTERISKS DENOTE OMISSIONS.

THIS AGREEMENT is made on 13th March, 1998 BETWEEN:

     (1) GRASEBY LIMITED  registered number 894638 whose registered office is at
765 Finchley Road, London NW11 8DS (the "Seller");

     (2) THERMO ENVIRONMENTAL INSTRUMENTS INC. whose principal place of business
is   at   8   West   Forge   Parkway,   Franklin,   Massachusetts   02038,   USA
("Environmental");

     (3) THERMO  SENTRON INC. whose  principal  place of business is at 501 90th
Avenue, NW, Minneapolis, Minnesota 55433, USA ("Sentron");

     (4) SMITHS  INDUSTRIES plc registered number 137013 whose registered office
is at 765 Finchley Road, London, NW11 8DS (the "Seller's Guarantor"); and

(5)      THERMO ELECTRON  CORPORATION whose principal place of business is at 81
         Wyman Street, Waltham,  Massachusetts 02254-9046, USA (the "Purchasers'
         Guarantor").

WHEREAS:

(A)      Graseby Allen Limited  ("Allen") is a private company limited by shares
         short  particulars  of which are set out in Part A of Schedule 1 having
         an authorised  capital of  (pound)50,000  divided into 50,000  ordinary
         shares of (pound)1 all of which have been issued (the "Allen Shares").

(B)      Allen is the beneficial  owner of all the issued share capital of Allen
         Coding  Corporation  and 500 ordinary  shares in Svenska Allen AB and a
         member of the Graseby Group is the beneficial owner of 2,100 (certified
         ordinary)  shares  (the  "France  Shares")  in Allen  France SA ("Allen
         France") short details of each of which are set out in Parts A, B and C
         of Schedule 2 respectively.

(C)      Graseby Product Monitoring Limited ("Product  Monitoring") is a private
         company  limited by shares  short  particulars  of which are set out in
         Part B of Schedule 1 having an authorised  capital of  (pound)2,000,000
         divided into 1,500,000  redeemable ordinary shares of (pound)1 each and
         500,000  ordinary shares of (pound)1 each all of which have been issued
         (the "Product Monitoring Shares").

(D)      Product  Monitoring  is the  beneficial  owner of all the issued  share
         capitals of Graseby Best Limited and Graseby  Intertest  Limited  short
         particulars  of each of which are set out in Parts I and J respectively
         of Schedule 2.
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(E)      Goring Kerr Detection  Limited  ("Goring Kerr  Detection") is a private
         company  limited by shares  short  particulars  of which are set out in
         Part C of  Schedule 1 having an  authorised  capital  of  (pound)26,000
         divided into 20,000  redeemable  ordinary  shares of (pound)1  each and
         6,000  ordinary  shares of (pound)1  each all of which have been issued
         (the "Goring Kerr Detection Shares").

(F)      Graseby Goring Kerr Inc.  ("Goring Kerr") is a company  incorporated in
         the United  States of  America  under the laws of the State of New York
         short  particulars  of which are set out in Part D of Schedule 1 having
         an  authorised  share  capital of 200 common stock of no par value each
         divided into 200 shares (the "Goring Kerr Shares").

(G)      Goring Kerr Detection is the  beneficial  owner of all the issued share
         capitals  of Graseby  Goring  Kerr (NZ)  Limited,  Graseby  Goring Kerr
         Canada Inc. and Graseby  Product  Monitoring GmbH short details of each
         of which are set out in Parts D, E and F respectively of Schedule 2.

(H)      Graseby Andersen Inc. ("Andersen Inc") is a company incorporated in the
         United States of America under the laws of the State of Delaware  short
         particulars  of which  are set out in Part E of  Schedule  1 having  an
         authorised  share  capital of US$25,000  divided into 25,000  shares of
         US$1 each of which 4,886  shares have been  issued (the  "Andersen  Inc
         Shares").

(I)      Andersen Inc. is the  beneficial  owner of all the issued share capital
         of Graseby  Specac  Limited short  particulars  of which are set out in
         Part G of Schedule 2 and Graseby Specac Limited is the beneficial owner
         of all the  issued  share  capital of Graseby  Andersen  Limited  short
         details of which are set out in Part H of Schedule 2.

(J)      The Seller is beneficially entitled to all the issued share capitals of
         Allen,  Product  Monitoring,  Goring  Kerr  Detection,  Goring Kerr and
         Andersen Inc.

(K)      The Seller wishes to sell and the Purchasers wish to purchase the Allen
         Shares, France Shares, Product Monitoring Shares, Goring Kerr Detection
         Shares,  Goring Kerr Shares and Andersen Inc.  Shares (the "Shares") on
         the terms and subject to the conditions set out in this agreement.

(L)      The Seller's  Guarantor and the  Purchasers'  Guarantor  have agreed to
         guarantee  the  obligations  in this  agreement and the Tax Deed of the
         Seller and the Purchasers respectively.
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IT IS AGREED  as follows:

INTERPRETATION

(1)      In this agreement:

         "Accountants' Reports" means the financial review reports dated January
         1998 prepared by Price Waterhouse in the Agreed Form;

         "Accounts Date" means 1st October, 1997;

         "Agreed  Form"  means,  in relation to any  document,  the form of that
         document which has been initialled for the purpose of identification by
         the Seller's Solicitors and the Purchasers' Solicitors;

          "Base Rate"  means the base rate from time to time of National 
          Westminster Bank plc;

          "business  day" means a day (other than a Saturday or Sunday) when 
          banks in London are open for business;

         "Companies" means the companies  referred to in Schedule 1 and Parts A,
         and D to J inclusive, of Schedule 2 and "Company" means any of them;

         "Companies'  Loans"  means  the  sum of  (pound)12,423,740  owed by the
         Companies to members of the  Seller's  Group as set out in the document
         in the Agreed Form, to be repaid on Completion;

          "Completion"  means  completion  of the sale and  purchase of the 
          Shares in accordance with clause 8;

         "Completion  Accounts"  means the Draft  Completion  Accounts as agreed
         under clause 3B or as adjusted  following  determination of any item in
         dispute pursuant to that clause;

         "Disclosure Letter" means the letter from the Seller to the Purchasers 
          dated the date of this agreement in the Agreed Form;

         "Draft Completion Accounts" shall have the meaning assigned to it in 
          clause 3B(4);

         "Graseby Group" means the Seller and any of its subsidiaries other 
          than the Companies;

         "Indemnified  Claims"  means the  Molins  Claim and the Owens  Brockway
         Claim as described in Part I A.15 and Part IV A.15  respectively of the
         Disclosure Letter;
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         "Information  Memoranda" means the confidential  information  memoranda
         dated  December,  1997  prepared by Robert  Fleming & Co Limited in the
         Agreed Form;

         "Intellectual Property Rights" means all rights in inventions, patents,
         copyrights,  design rights,  trade marks and trade names, service marks
         (excluding  in each case the Graseby  name and any marks  incorporating
         the "Graseby"  name),  trade secrets,  know-how and other  intellectual
         property  rights   (whether   registered  or   unregistered)   and  all
         applications for them anywhere in the world;

         "Leases" means the leases in respect of each of the leasehold
          Properties;

         "Named Individuals" means each of the following persons: Stephen 
          Aubrey, Simon Bell, Neil Burdett, John Cooper, Roger Ellis, Jonathan
          Flint, David Flowerday, Carole Fyffe, Steve Holmes, Peter Mason,
         John Roberts and Steve Warren;

         "Net Assets  Statement"  means the Draft Net Assets Statement as agreed
         under clause 3B or as adjusted  following  determination of any item in
         dispute pursuant to that clause;

         "Properties"  means the properties  shortly described in Schedule 4 and
         "Property" means any of them and includes every part of each of them;

         "Purchasers" means Environmental and Sentron and "Purchaser" shall 
          mean either of them;

         "Purchasers' Group" means the Purchasers' Guarantor and all of its 
          subsidiaries, other than the Companies;

         "Purchasers' Solicitors" means Warner Cranston of Pickfords Wharf, 
          Clink Street, London SE1 9DG;

         "Seller's Accountants" means Price Waterhouse of No 1 London Bridge, 
          London;

         "Seller's Group" means the Seller's Guarantor and all of its 
          subsidiaries (other than the Companies);

         "Seller's Loans" means the sum of (pound)3,684,059  owed by one or more
         members  of the  Seller's  Group  to the  Companies  as set  out in the
         document in the Agreed Form, to be repaid on Completion;
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         "Seller's Solicitors" means Allen & Overy of One New Change, London 
          EC4M 9QQ;

         "Severance Costs" means the sum of (pound)74,525  payable in respect of
         the  termination  of the  employment  of certain  employees  of Product
         Monitoring as referred to in the list in the Agreed Form;

         "subsidiary" means a subsidiary for the purposes of section 736 of the 
          Companies Act 1985;

         "Tax Deed" means the Tax Deed in the Agreed Form; and

         "Warranties" means the warranties by the Seller contained in clause
          6(1) and Schedule 6.

(2) Any reference, express or implied, to an enactment includes references to:

         (a)      that enactment as amended, extended or applied by or under
                  any other enactment before or after this agreement;

         (b)      any enactment which that enactment re-enacts (with or without
                  modification); and

         (c)      any  subordinate   legislation  made  (before  or  after  this
                  agreement)  under any  enactment,  including one within (a) or
                  (b) above,

         save that this  subclause  shall not have  effect  insofar  as it would
         create or increase any  liability  of the Seller  under this  agreement
         beyond that at the date of this agreement.

(3)      A person shall be deemed to be connected with another if that person is
         connected  with another within the meaning of section 839 of the Income
         and Corporation Taxes Act 1988.

(4)      Words  denoting  persons shall include bodies  corporate and  
         unincorporated associations of persons.

(5)      Any  reference  to "so  far as the  Seller  is  aware"  or any  similar
         expression  shall refer to any knowledge or belief which the Seller has
         or would have if it had made all usual and reasonable enquiries of:

     (a) Terry Summers and David Blacket in respect of Allen;
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     (b) Timothy Coombs,  Thomas  Ainscough and Alice Dunn in respect of Product
Monitoring;

     (c)  Timothy  Coombs and Alice Dunn in  respect of Goring  Kerr  Detection,
Graseby Product Monitoring GmbH and Graseby Goring Kerr (NZ) Limited;

     (d) David  Johnson,  Benjamin Chu, Alice Dunn and Timothy Coombs in respect
of Goring Kerr and Graseby Goring Kerr Canada Inc.;

     (e) David Morell and Graham Young in respect of Andersen Inc.;

     (f) Andrew  Little and  Nicholas  Chamberlin  in respect of Graseby  Specac
Limited and Graseby Andersen Limited; and

     (g) Timothy Coombs,  Alice Dunn and Thomas  Ainscough in respect of Graseby
Best Limited and Graseby Intertest Limited,

     and in each of the above cases requiring such persons where  appropriate to
have made the same enquiries of the appropriate managers and senior employees in
the relevant Company.

(6)      Subclauses (1) to (5) apply unless the contrary intention appears.

(7) The headings in this agreement do not affect its interpretation.

SALE AND PURCHASE OF THE SHARES

(1)      Subject to clause 4 the Seller shall sell (or in the case of the France
         Shares shall procure the sale of) and each Purchaser shall purchase the
         Shares set out below against its name free from  encumbrances  together
         with all rights attaching to them:

     (a) Sentron:the  Allen Shares,  the France Shares,  the Product  Monitoring
Shares, the Goring Kerr Detection Shares and the Goring Kerr Shares; and

         (b)      Environmental:    the Andersen Inc. Shares.
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(2) The Seller covenants with each Purchaser that:

         (a)      it has the  right to sell and  transfer  the  full  legal  and
                  beneficial  interest  in the  Shares  (other  than the  France
                  Shares)  to each  Purchaser  and,  in the  case of the  France
                  Shares,  it has the right to procure the sale and  transfer of
                  the full  legal  and  beneficial  interest  in such  Shares to
                  Sentron, all on the terms set out in this agreement; and

         (b)      on or after  Completion  it  will,  at the  Seller's  cost and
                  expense, execute and do (or procure to be executed and done by
                  any other necessary party) all such deeds, documents, acts and
                  things as either  Purchaser  may from time to time  reasonably
                  require  in order to vest any of the  Shares  in the  relevant
                  Purchaser or as otherwise may be necessary to give full effect
                  to this agreement.

(3)      Neither  Purchaser  shall be obliged to complete the purchase of any of
         the  Shares  unless  the  purchase  of  all  the  Shares  is  completed
         simultaneously in accordance with this agreement.

3A.                      INITIAL CONSIDERATION

         The initial  consideration  for the sale of the Shares shall be the sum
         of (pound)35,260,319 (the "Initial  Consideration")  payable in cash on
         Completion and apportioned between the Shares as follows:

         (a)      for the Allen Shares, the sum of (pound)9,000,000;

         (b)      for the France Shares, the sum of (pound)70,000;

         (c)      for the Product Monitoring Shares, the sum of (pound)1,500,000
                  for   the   redeemable   ordinary   shares   and  the  sum  of
                  (pound)12,755,990 for the ordinary shares;

         (d)      for the Goring Kerr Detection Shares, the sum of (pound)20,000
                  for   the   redeemable   ordinary   shares   and  the  sum  of
                  (pound)3,980,000 for the ordinary shares;

         (e)      for the Goring Kerr Shares, the sum of (pound)1,000,000; and

         (f) for the Andersen Inc. Shares, the sum of (pound)6,934,329.
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3B.                      CONSIDERATION ADJUSTMENT

(1)      If the Net  Operating  Assets  exceed  (pound)11,244,000  the  relevant
         Purchaser  shall  (subject to the terms of this  agreement)  pay to the
         Seller by way of  deferred  consideration  for the sale of the Shares a
         sum (the  "Deferred  Consideration")  equal  to the  excess  over  that
         amount. If the Net Operating Assets are less than (pound)11,244,000 the
         Seller  shall  (subject  to the  terms  of this  agreement)  pay to the
         relevant  Purchaser by way of reduction  to the  consideration  for the
         sale of the Shares a sum (the  "Deficit")  equal to the shortfall below
         that amount.  The relevant Purchaser shall be notified to the Seller by
         the Purchasers'  Guarantor and failing such  notification  within three
         business  days  after the date on which  the Net  Assets  Statement  is
         agreed or determined under this clause the relevant  Purchaser shall be
         such Purchaser as the Seller decides.

(2)      For this purpose "Net  Operating  Assets" means the aggregate  sterling
         value of all assets (less  liabilities) of the Companies as at the date
         of Completion excluding:

         a)    all cash balances and bank overdrafts
         b)    all external borrowings
         c)    all inter company or intra-group balances, including the Seller's
               Loans and the Companies' loans but excluding those relating to 
               day to day trading activities 
         d)    all pension related assets and liabilities
         e)    all share capital and reserves
         f)    all goodwill and other intangible assets including intellectual 
               property rights

     as shown in the Net  Assets  Statement  agreed  or  determined  under  this
clause.

(3)      As  soon as  practicable  and in any  event  within  75 days  following
         Completion each Purchaser shall procure that the Companies  acquired by
         it  deliver  to that  Purchaser  the  balance  sheets as at  opening of
         business on the date of Completion (the  "Completion  Balance  Sheets")
         prepared in accordance with the convention(s) and accounting principles
         and  practices  set out in Schedule 5 ("Agreed  Rules").  Within  three
         business days of receipt of the Completion  Balance Sheets the relevant
         Purchaser  shall  deliver  the  same  to the  Seller  together  with an
         aggregated  balance sheet in which the  Completion  Balance Sheets have
         been  aggregated  ("Aggregated  Balance  Sheet").  There  shall also be
         prepared  by the  Purchasers  and  delivered  by them to the  Seller  a
         statement of cash book  balances of each of the Companies as at opening
         of business on the date of  Completion  being a summary of the balances
         on  each  of  the  Companies'   bank  accounts  (shown  by  their  bank
         statements)  adjusted to reflect  cheques  drawn but not  presented and
         deposits  made but not  reflected  on the  Companies'  bank  statements
         ("Cash Book Statements").
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(4)      Upon  receipt  of the  Completion  Balance  Sheets  and the  Aggregated
         Balance  Sheet by the Seller,  the Seller  shall  instruct the Seller's
         Accountants to prepare as soon as is reasonably  practicable and in any
         event within 45 days following receipt of the Completion Balance Sheets
         a  statement  of the  Net  Operating  Assets  (the  "Draft  Net  Assets
         Statement")  together with a report indicating their agreement with, or
         suggested  adjustments to (as the case may be) the  Completion  Balance
         Sheets and the  Aggregated  Balance Sheet and the Cash Book  Statements
         (the "Draft  Completion  Accounts") so as to make the same conform with
         the Agreed Rules.

(5)      The Purchaser shall procure that the Seller's Accountants are given all
         such  access  to the  premises  and  financial  and other  records  and
         documents  of the  Companies  as  are  necessary  for  the  purpose  of
         preparing  the  Draft Net  Assets  Statement  and the Draft  Completion
         Accounts and shall  procure that the  directors  and  employees of each
         Company promptly provide the Seller's  Accountants with all information
         and explanations as they may reasonably request in connection with such
         preparation and determination.

(6)      The  Seller  shall  deliver  to  each  Purchaser  a copy  of the  Draft
         Completion  Accounts  and  Draft  Net  Assets  Statement  within  three
         business days after they are prepared.

(7)      Within 14 days of delivery of the Draft  Completion  Accounts and Draft
         Net Assets  Statement  as referred  to in  subclause  (6) above  either
         Purchaser  may  notify  the Seller in writing of any item or items they
         wish to dispute.  If no such  notice is  received by the Seller  within
         such 14 day period the  Purchasers  shall each be deemed to have agreed
         the Draft Completion Accounts and the Draft Net Assets Statement.

(8)      Upon  receipt  by the  Seller  of a notice  of any item of  dispute  in
         accordance  with  subclause  (7)  above  the  Seller  and the  relevant
         Purchaser  shall  use all  reasonable  endeavours  to agree  the  Draft
         Completion  Accounts  and the Draft Net  Assets  Statement  in  writing
         within 14 days of  delivery of such  notice  failing  which the item or
         items in dispute shall be determined by:
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     (a) such firm of chartered accountants as the parties may agree in writing;
or

     (b) failing agreement on the identity of the firm of chartered  accountants
within a further seven days from the expiry of the period of 14 days referred to
above,  such firm of independent  chartered  accountants as may be appointed for
this purpose on the  application of any party to this agreement by the President
for the time being of the  Institute  of  Chartered  Accountants  in England and
Wales.

     (9) The accountants appointed under subclause (8) above (the "Accountants")
shall act on the following basis:

         (a)      the Accountants shall act as experts and not as arbitrators;

         (b)      their terms of reference shall be to determine, within 30 days
                  of  their  appointment,  an  amount  which  in  their  opinion
                  represents  under and in accordance  with the Agreed Rules the
                  item or items in  dispute,  as  notified to them in writing by
                  either the relevant Purchaser(s) or the Seller;

         (c)      the  Seller  and  the   Purchasers   shall  each  provide  the
                  Accountants with all information which they reasonably require
                  and the  Accountants  shall be  entitled  (to the extent  they
                  consider  it  appropriate)  to  base  their  opinion  on  such
                  information  and on the  accounting  and other  records of the
                  Companies;

     (d) the  determination of the Accountants shall (in the absence of manifest
error) be conclusive; and

         (e) their costs shall be borne equally between the parties.

(10)     The amount of any Deferred  Consideration  or Deficit,  as the case may
         be,  together  with accrued  interest  calculated  in  accordance  with
         subclause  (12)  shall be payable  within  seven days of the Net Assets
         Statement being agreed or ascertained under the above  provisions.  The
         amount of such Deferred  Consideration or Deficit,  shall be reduced or
         increased as the case may be by an amount equal to 69 per cent.  of the
         Severance  Costs to the extent that such Severance  Costs have not been
         paid before  Completion.  At the same time, the Purchasers shall pay to
         the  Seller  by way of  additional  consideration  for the  sale of the
         Shares a sum equal to the amount (if any) by which the aggregate of the
         cash balances as shown on the Cash Book Statements exceeds the sum paid
         on account under clause 9(3). If such  aggregate cash balances are less
         than the sum paid on account under clause 9(3),  the Seller shall repay
         to the Purchasers a sum equal to the shortfall.
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(11)     If a Purchaser has notified the Seller of a bona fide Warranty Claim in
         accordance  with  the  provisions  of this  agreement  then it shall be
         entitled to deduct the amount of such Warranty  Claim from any Deferred
         Consideration  due to the  Seller and pay it into an  interest  bearing
         escrow  trust  account  to be  opened  jointly  in the  names  of  that
         Purchaser and the Seller.  Upon settlement or  determination by a court
         of such Warranty  Claim the amount (if any) of the Warranty  Claim that
         is  agreed  between  the  Seller  and that  Purchaser  or is  otherwise
         determined  as  being  due to that  Purchaser  shall be  repaid  to the
         Purchaser  (together  with  interest  accrued  thereon) from the escrow
         account and any balance (together with interest accrued thereon) in the
         escrow account shall be paid to the Seller.

(12)     Interest  shall  accrue  on a daily  basis on the  amount  of  Deferred
         Consideration  or  Deficit  (as the case may be) at the rate of two per
         cent.  above the Base Rate for the period  from the date of  Completion
         until  payment  is made in  accordance  with this  clause  (both  dates
         inclusive).

3C.                      INDEMNITY

     (1)  The  Seller  agrees  to  indemnify  and  hold  harmless  the  relevant
Purchasers  against 50 per cent. of all liabilities,  costs and expenses arising
out of the Indemnified Claims.

     (2) The relevant Purchasers shall take such action to avoid, dispute,
         resist, appeal,  compromise or contest the liability of the Indemnified
         Claims as may  reasonably  be  requested by the Seller and shall ensure
         that the Companies  co-operate  with the Seller in relation to the same
         and give the Seller full and prompt access to their relevant employees,
         documents,  records and  premises  where  reasonably  requested  by the
         Seller.

3D.  **** CLAIM

     (1) The Seller shall  indemnify  Product  Monitoring in respect of the ****
Claim on the terms of this clause.
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(2)      The  Seller  and  Sentron  shall  regularly  consult  with  each  other
         regarding  developments  in  respect  of the ****  Claim  and,  without
         prejudice to subclause (3), shall co-operate  together with a view to a
         satisfactory  resolution  thereof  and  with a view to  minimising  the
         adverse effect of the **** Claim on the business of Product Monitoring.

(3)      Sentron shall procure that the Seller shall have the exclusive  conduct
         on behalf of Product  Monitoring of all  negotiations,  discussions and
         legal  proceedings  between Product  Monitoring and **** relating to or
         arising out of the **** Claim including  negotiations  for the grant by
         **** to Product Monitoring of a licence to use the Patent (such licence
         to be for a term not  expiring  before  **** and  otherwise  upon terms
         (save  as to  payments  due to ****  thereunder  by way of  royalty  or
         similar   such   payments)   reasonably   satisfactory   to   Sentron).
         Accordingly, Sentron shall procure that Product Monitoring shall:

         (a)      co-operate  with  the  Seller  and keep  the  Seller  promptly
                  informed of all  communications  received from **** in respect
                  of the **** Claim;

         (b)      give the Seller  full access at all  reasonable  times to, and
                  copies of, relevant documents, records, employees and premises
                  for purposes relating to the **** Claim;

         (c)      immediately upon request by the Seller undertake with **** not
                  to make any further  sales of the **** in the United States of
                  America;

         (d)      within seven days of any request by the Seller,  cease to make
                  any further sales of the **** in the United States of America;

         (e)      cease  to make  sales of such  **** in the  United  States  of
                  America if an  injunction  is granted to **** which  restrains
                  such sales by Product Monitoring;

         (f)      enter  into such  licence  to use the Patent as the Seller may
                  agree, on Product  Monitoring's  behalf, with **** (subject to
                  the foregoing  provisions of this  subclause in respect of the
                  terms of such licence); and

         (g)      not  admit,  settle or  compromise  the **** Claim or take any
                  action  in  connection  with  the  ****  Claim  other  than as
                  directed by the Seller.

(4) The Seller shall cease to be liable under this clause immediately upon:
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     (a) Sentron failing to comply with subclause (3)(c)(d) or (e) above; or

         (b)      the  Patent   being   determined   by  a  court  of  competent
                  jurisdiction or regulatory body to be not valid; or

         (c)      Product  Monitoring  voluntarily  ceasing to endeavour to make
                  sales of the **** in the United States of America; or

         (d)      Product Monitoring agreeing a full and final settlement of the
                  ****  Claim  with  ****  (provided  all  costs,  expenses  and
                  liability  in  respect  of such  settlement  are  borne by the
                  Seller),

         save (i) for any  liabilities  which the Seller may have incurred under
         this clause up to the time of the event in (a), (b), (c) or (d) of this
         subclause  and (ii) that the Seller  shall bear any costs  incurred  by
         Product  Monitoring at the Seller's direction in resisting the validity
         of the Patent to the extent  that such costs are not  recoverable  from
         **** following the  determination  referred to in paragraph (b) of this
         subclause.

(5)      If the Seller, on behalf of Product Monitoring, procures the grant of a
         licence  from **** (which  shall be on the terms  outlined in subclause
         (3) above) to Product Monitoring to use the Patent up to ****:

     (a) Sentron  shall  procure that Product  Monitoring  shall comply with the
terms of such licence;

         (b)      provided Sentron complies with paragraph (a) above, the Seller
                  shall bear any royalty fees and other similar payments payable
                  under such licence;

         (c)      save as provided in paragraph (b) and without prejudice to any
                  liabilities  of the Seller under this clause accrued up to the
                  effective date of such licence, the Seller shall cease to have
                  any further liability under this clause.

(6)      Without  prejudice  to the other  provisions  of this clause other than
         subclause  (1),  the  Seller's  liability  under this  clause  shall be
         limited as follows:

         (a)      any costs and expenses of legal  advisers or patent  attorneys
                  or agents  engaged by Sentron  or Product  Monitoring  to deal
                  with the **** Claim shall be borne by the Seller,  but only to
                  the extent previously agreed in writing by the Seller;
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         (b) the  Seller  shall  bear any  liability  which  Product  Monitoring
either:

                  (i)      agrees  in  writing  with  **** as its  liability  in
                           respect of the **** Claim provided Product Monitoring
                           has acted in  accordance  with the  Seller's  written
                           directions in making such agreement; or

                  (ii)     is  determined  by a court of competent  jurisdiction
                           (where no appeal can be made or the Seller elects not
                           to pursue such  appeal) to have to **** in respect of
                           the **** Claim;

         (c)      if Product  Monitoring is obliged by an injunction issued by a
                  court of  competent  jurisdiction  or by  agreement  with ****
                  (entered  into at the direction of the Seller) or by direction
                  of the Seller issued under  subclause  (3)(d) to cease selling
                  the **** in the United States of America, the Seller shall pay
                  to Product Monitoring:

                  (i)      a sum equal to  US$****  per day for the period (the
                           "Shutdown  Period")  from the date of such  cessation
                           until the  earlier  of (i) **** and (ii) the date (if
                           any) on which Product  Monitoring is permitted  under
                           such injunction or agreement (but not such direction)
                           to recommence  sales of the **** in the United States
                           of America; and

                  (ii)     US$**** if the Shutdown Period is four months or 
                           more; and

                  (iii) a  further  US$****  if the  Shutdown  Period  is six
months or more.

(7)      The  Seller's  liability  under this clause shall cease on **** save in
         respect of any such liability accrued before that date.

(8)      For the avoidance of doubt, no payments by the Seller under this clause
         shall  constitute  a  reduction  in the  consideration  payable for the
         Product Monitoring Shares.

(9) For the purposes of this clause 3D the following  expressions shall have the
following meaning:

         "****" means ****;
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     "**** Claim" means the alleged  claim by **** that the ****  infringes  the
Patent;

         "Patent" means ****'s patent (US **** of ****); and

     "****" means the **** of Product Monitoring the subject of the **** Claim.

4.    CONDITIONS PRECEDENT

     (1) The sale and purchase of the Shares is conditional on:

         (a)      the  necessary   regulatory   filing  having  been  made,  all
                  appropriate   waiting  periods  and  any  other  time  periods
                  (including   extensions   thereto)  under  the  United  States
                  Hart-Scott-Rodino Antitrust Improvements Act 1976 (as amended)
                  and the regulations made thereunder having expired,  lapsed or
                  been  terminated  in  respect of the  change of  ownership  of
                  Goring Kerr and Andersen Inc.; and

         (b)      the  necessary  regulatory  filing  having  been  made and the
                  parties  having  obtained  formal  clearance  from the  German
                  Federal Cartel Office in respect of the change of ownership of
                  Graseby Product Monitoring GmbH.

     (2) The Purchasers may waive either or both of the conditions (a) to (b) in
subclause  (1) above in whole or in part at any time by notice in writing to the
Seller.

     (3) Each of the parties shall use reasonable endeavours to procure that the
conditions  in subclause (1) above are fulfilled on or before 15th May, 1998 and
each of the parties agrees to assist in the preparation of all necessary filings
with,  attending  meetings  with or speaking to (if  necessary)  the  regulatory
authorities referred to in subclause (1) above.

     (4) If the conditions in subclause (1) above are not fulfilled or waived on
or  before  the date  specified  in  subclause  (3) all of the  clauses  of this
agreement  shall cease to have effect  (save in respect of  subclause  (3),  and
clauses 1, 15, 16,  18(5),  19 and 20 which shall  survive  termination  of this
agreement).

5.        COVENANTS UP TO COMPLETION

(1)      In the period from the date of this  agreement  until  Completion,  the
         Seller shall  (insofar as it is within its power to do so) procure that
         except with the prior consent of the Purchasers:
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     (a) none of the  Companies  departs from the ordinary  course of its day to
day trading in any material respect;

     (b) none of the rights  attached to any shares in any Company is  modified,
no shares in any  Company  are  created or issued,  no option or rights over any
shares or uncalled capital of any Company is granted or agreed to be granted and
no obligations convertible into shares are created;

     (c) no alteration is made to the  memorandum or articles of  association of
any Company;

     (d) none of the Companies will:

     (i) incur any expenditure exceeding (pound)500,000 on capital account;

     (ii) declare, make or pay any dividend or other distribution;

     (iii) make any material  changes in the terms and  conditions of employment
of any of its senior  employees or employ or  terminate  (except for good cause)
the  employment  of any such  person (and for the  purposes of this  subclause a
senior employee shall mean a person earning more than (pound)40,000 per annum);

     (iv) permit any of its  insurances to lapse or knowingly do anything  which
would make any policy of insurance  void or voidable or materially  increase the
level of cover provided under such insurance policies;

     (v) admit any person  (other than  pursuant to this  agreement)  whether by
subscription or transfer or transmission as a member of that Company;

     (vi)  give  any  guarantee  or  indemnity  other  than  in  respect  of the
obligations of another Company or in the ordinary course of business;

     (vii)  acquire  any  shares  of any other  company  or  participate  in any
partnership or joint venture or agree to do so;
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     (viii) permit the  appointment of any person as a director of that Company;
or

     (ix)  discontinue or amend the Seller's  Scheme (other than as envisaged in
Schedule  4) or  commence  to  wind it up or  cease  to  admit  new  members  or
communicate to any employee any intention to do so; or

     (c) it will not  dispose  of any  interest  in the Shares or any of them or
grant any option or right of pre-emption over, or mortgage,  charge or otherwise
encumber the Shares or any of them.

(2)       Prior  consent  requested  from the  Purchasers  by the  Seller  under
          subclause (1) shall not be unreasonably withheld or delayed by the 
          Purchasers.

(3)      The  requirement  for consent shall not apply and this clause shall not
         be breached if (i) the Seller can demonstrate that it was necessary for
         it to take  the  relevant  action  without  obtaining  the  Purchasers'
         consent  first  due  to  emergency   requirements   which  would  cause
         significant  operational  difficulties  if not  remedied  before it was
         practicable to consult with and obtain consent of the  Purchasers;  and
         (ii) the Seller  notifies the  Purchasers of such action as soon as the
         Seller is reasonably able to do so.

(4)      Each  Purchaser  and any person whom it may  authorise for this purpose
         shall be allowed access upon reasonable notice to all the books and the
         records,  agreements and other documents and premises  belonging to any
         Company and the Seller shall supply any information reasonably required
         by the Purchaser relating to any Company.

(5)      The Seller shall in so far as it is able, use its reasonable endeavours
         (including  by  exercising  its  voting  rights)  to  ensure  that  the
         provisions of this clause are complied with in respect of Svenska Allen
         AB and Allen France as if each of them were a Company.

(6)      In the period  between the date of this agreement and  Completion,  the
         Purchasers  will use their  best  endeavours  to assist  the  Seller in
         procuring  that the  employment  contracts of A. Dunn, T. Coombs and T.
         Ainscough are transferred  from the Seller to Product  Monitoring,  and
         the  employment  contracts of G.R.  Young and R. White are  transferred
         from the Seller to Andersen Inc.
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6.        WARRANTIES

(1)      The Seller warrants to the Purchasers that save as fairly  disclosed in
         the  Disclosure  Letter each of the statements set out in Schedule 6 is
         true. The Seller  acknowledges  that the  Purchasers  have entered into
         this agreement in reliance upon,  amongst other things,  the Warranties
         and the  undertakings in clause 12. Save as provided in this agreement,
         the  Warranties  shall be  separate  and  independent  and shall not be
         limited  by  reference  to any  other  paragraph  in  Schedule  6 or by
         anything else in this agreement or the Tax Deed.

(2)      The Seller agrees with the  Purchasers  for  themselves and as trustees
         for each  Company  and  their  respective  employees  to  assign to the
         Purchasers  any  rights or claims  which it may have in  respect of any
         misrepresentation, inaccuracy or omission in or from any information or
         advice  supplied or given by any of the Companies or their employees in
         connection  with the giving of the Warranties and the  preparation  and
         entry into of this  agreement,  the Tax Deed and the Disclosure  Letter
         save that this shall not apply in case of fraud or in  relation  to any
         person who has ceased to be such an employee.

(3) The Purchasers acknowledge and agree that:

         (a)      the Warranties and the other  provisions of this agreement are
                  the only  warranties or other  assurances of any kind given by
                  or on behalf of the  Seller  and on which the  Purchasers  may
                  rely in entering into this agreement;

         (b)      no other  statement,  promise or forecast made by or on behalf
                  of the  Seller  may  form  the  basis  of,  or be  pleaded  in
                  connection  with,  any  claim  by  a  Purchaser  under  or  in
                  connection with this agreement; and

         (c)      any claim by a Purchaser or any person  deriving title from it
                  in connection  with the Warranties (a "Warranty  Claim") shall
                  be subject to the following provisions of this clause.

(4)      There shall be  disregarded  for all  purposes  any  Warranty  Claim in
         respect  of which the  amount of the  damages  to which the  Purchasers
         would otherwise be entitled is less than (pound)5,000; provided however
         that a series of related  claims or claims  based on the same facts and
         circumstances  shall for the purposes of this subclause be deemed to be
         a single  claim and the  damages in respect of each such claim shall be
         aggregated in determining whether they exceed (pound)5,000.
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(5) The liability of the Seller in respect of the Warranties:

     (a) shall not (when aggregated with any liability under the Tax Deed) arise
unless the amount of all claims made in respect of the Warranties and/or the Tax
Deed (or which would have been made but for the  operation of this  paragraph or
the  corresponding  provision  in the Tax Deed and  excluding  also those claims
referred to in subclause  (4))  exceeds(pound)500,000  but if liability  exceeds
that  figure  then all claims  including  claims  previously  notified  shall be
counted and for this  purpose any  reduction  in such claim  resulting  from the
operation  of clause 8(4) of the Tax Deed shall not prevent the  Purchaser  from
being able to make a Warranty  Claim should the reduced  level of such  Warranty
Claim be less than(pound)500,000; and

         (b)      shall not (when  aggregated  with any liability  under the Tax
                  Deed) exceed the aggregate amount of the Initial Consideration
                  as  adjusted  pursuant  to clause  3B and any sums paid  under
                  clauses 9(3) and 3(10); and

         (c)      shall not arise to the extent  that the matter  giving rise to
                  the breach is the subject of a claim under the Tax Deed.

(6)      The Seller shall cease to have any liability under or in respect of the
         Warranties 18 months after the date of Completion  except in respect of
         a Warranty Claim of which a Purchaser gives notice to the Seller before
         the expiry of such period and in  accordance  with  subclause (8) below
         but the liability of the Seller in respect of any Warranty  Claim shall
         absolutely  terminate  if  proceedings  in  respect of it have not been
         commenced  and served on the Seller  within  nine  months of service of
         notice of that Warranty Claim.

(7) Neither Purchaser shall be entitled to make any Warranty Claim:

         (a)      to the extent that  provision or  allowance  for the matter or
                  liability  which  would  otherwise  give  rise to the claim in
                  question  has been made or falls to be made in the  Completion
                  Accounts or it is otherwise taken account of, or reflected in,
                  the Completion Accounts;
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         (b)      if the  claim  would  not  have  arisen  but for a  change  in
                  legislation  made  after  Completion   (whether   relating  to
                  taxation, rates of taxation or otherwise) or the withdrawal of
                  any extra-statutory  concession  previously made by the Inland
                  Revenue  or any other  taxing  authority  (whether  or not the
                  change purports to be effective retrospectively in whole or in
                  part); or

         (c)      to the extent  that the claim  arises as a result  only of any
                  change after Completion in the accounting bases upon which any
                  of the Companies values its assets.

(8)      If a Purchaser or any of the Companies  becomes aware of a matter which
         could give rise to a Warranty Claim that Purchaser shall give notice of
         the relevant facts to the Seller as soon as reasonably  practicable and
         in any event within 30 days of that  Purchaser  becoming aware of those
         facts and (subject to the provisions of the Tax Deed in relation to any
         matter  which may form the subject of a claim under it) if the claim in
         question is as a result of or in connection with a liability or alleged
         liability to a third party that  Purchaser  (at the  Seller's  expense)
         shall procure the Companies or the relevant one or more of them to take
         such action to avoid, dispute,  resist,  appeal,  compromise or contest
         the  liability as may  reasonably  be requested by the Seller  provided
         that nothing in this clause 6(8) shall oblige the relevant Purchaser to
         take any action  which might  reasonably  be expected to be  materially
         prejudicial  to the  business  of the  Company.  In any case  where the
         relevant  Purchaser  is not so obliged to take or procure the taking of
         any action,  and liability on the Seller either arises under a Warranty
         Claim or is  greater  than it would  have been if such  action had been
         taken,  the  Seller  shall  not be  liable in  respect  of either  such
         Warranty  Claim or to the extent that such liability is greater than it
         so would have been.

(9)      Without  prejudice  to the  Purchasers'  duty to  mitigate  any loss in
         respect  of any breach of the  Warranties,  if in respect of any matter
         which would  otherwise  give rise to a breach of the  Warranties one of
         the  Companies is entitled to claim under any policy of  insurance  (or
         would have been so  entitled  had it  maintained  in force its level of
         insurance cover current at Completion)  the amount of insurance  monies
         which  that  Company  actually  recovers  shall  reduce  pro  tanto  or
         extinguish  the claim for breach of the  Warranties  and the Purchasers
         undertake to use their reasonable endeavours to recover such monies.
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(10)     If the Seller  makes any  payment  by way of damages  for breach of the
         Warranties  (the  "Damages  Payment")  and any of the  Companies or the
         Purchasers  receives any benefit  otherwise  than from the Seller which
         would not have been  received but for the  circumstance  giving rise to
         the  claim in  respect  of which  the  Damages  Payment  was made  that
         Purchaser  shall,  once it or the relevant  Company has  received  such
         benefit, forthwith repay to the Seller an amount equal to the lower of:
         (i) the amount of such benefit (less any  reasonable  costs or expenses
         incurred by the  relevant  Purchaser  or a Company in  recovering  such
         benefit); and (ii) the Damages Payment.

(11)     To the extent that the  Purchasers or the Companies do any act or thing
         after Completion  (other than in the ordinary course of business of the
         Companies  or as required by law) which gives rise to a Warranty  Claim
         which  would not  otherwise  arise where the  Purchasers  were aware or
         ought  reasonably  to have been aware such act or thing would be likely
         to give rise to a Warranty Claim,  the Purchasers  shall not be able to
         recover any sums in respect of such Warranty Claim.

(12)     Any payment made by the Seller in respect of a breach of the Warranties
         or a liability  under the Tax Deed shall be deemed to be a reduction in
         the consideration paid for the Shares.

(13)     The  provisions  of this clause shall have effect  notwithstanding  any
         other provisions of this agreement.

(14)     None of the limitations  contained in clauses 6(4) to 6(12) shall apply
         to any claim  which  arises as the  consequence  of, or is delayed as a
         result of fraud by the Seller or by any member of, or  employee  of any
         member of, the Seller's Group.

(15) Each of the Purchasers and the Purchasers' Guarantor warrants to the Seller
that:

         (a)      they are  corporations  validly existing under the laws of the
                  state  of  their   incorporation   with  requisite  power  and
                  authority  to enter  into and  perform,  and  have  taken  all
                  necessary  corporate  action to authorise  the  execution  and
                  performance  of,  their  respective   obligations  under  this
                  agreement and the Tax Deed;
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         (b)      this   agreement  and  the  Tax  Deed  will,   when  executed,
                  constitute  valid  and  binding  obligations  of  each  of the
                  Purchasers and the Purchasers'  Guarantor  enforceable against
                  them in accordance with their terms; and

         (c)      other   than   as   contemplated   by   this   agreement,   no
                  announcements,  consultations, notices, reports or filings are
                  required to be made by any member of the Purchasers'  Group in
                  connection   with  the   transactions   contemplated  by  this
                  agreement  nor are  any  consents,  approvals,  registrations,
                  authorisations  or  permits  required  to be  obtained  by any
                  member  of  the  Purchasers'  Group  in  connection  with  the
                  execution and  performance  of this  agreement or the Tax Deed
                  the failure to make or obtain any of which would:

                  (i)      prevent or delay completion of this agreement; or

                  (ii)     subject the Seller to any liability.

(16)     Without prejudice to subclause (5)(a) above the liability of the Seller
         in  respect of any  Warranty  Claim or a  liability  under the Tax Deed
         shall be reduced pro tanto or extinguished altogether,  as appropriate,
         to the extent of any overprovision determined in accordance with clause
         8 of the Tax Deed.

7.        TAX DEED

         The Seller shall on  Completion  enter into a Tax Deed in favour of the
Purchasers.

8.        COMPLETION

(1)      Completion  shall take place at the offices of the Seller's  Solicitors
         as soon as practicable  after and in any event within two business days
         after  satisfaction  (or waiver) of the conditions in clause 4(1) or on
         such other date as the Seller and the Purchasers may agree in writing.

(2) At Completion the Seller shall procure:

         (a)      the delivery to the Purchasers of:

                  (i)      duly executed  transfers in favour of the  Purchasers
                           or their  nominee(s)  of the  Allen  Shares,  Product
                           Monitoring Shares and Goring Kerr Detection Shares;
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                  (ii)     the share certificates representing the Allen Shares,
                           Product Monitoring Shares and Goring Kerr Shares;

                  (iii)    a duly executed  transfer ("ordres de mouvements") in
                           favour of the  Purchaser  in  respect  of the  France
                           Shares;

                  (iv)     stock certificates representing the Goring Kerr 
                           Shares and the Andersen Inc. Shares duly endorsed by 
                           the Seller in favour of the Purchaser;

                  (v)      the  certificates  of  incorporation,   common  seal,
                           minute books,  cheque books,  statutory registers and
                           share certificate books of the Companies;

                  (vi)     the title deeds and documents, relating to the 
                           Properties, that are in the Seller's possession;

                  (vii)    the Tax Deed duly executed by the Seller;

                  (viii)   the  resignations  of Alan Smith and Neil  Burdett as
                           directors  and/or  secretaries of the  Companies,  in
                           each case acknowledging by way of deed that they have
                           no claim  against the  Companies  whether for loss of
                           office or otherwise;

                  (ix)     the  resignation of the auditors of each Company with
                           acknowledgements  by them  that  they  have no  claim
                           against  the  Company  and,  where  applicable,   the
                           statement referred to in section 394 of the Companies
                           Act   1985  to  the   effect   that   there   are  no
                           circumstances  connected with their resignation which
                           they consider  should be brought to the notice of the
                           members or creditors of the Company; and

                  (x)      evidence reasonably satisfactory to each of the 
                           Purchasers that it has repaid the Seller's Loans;

         (b) that board  meetings of each of the  Companies are held at which it
is resolved that:
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                  (i)      the resignations  referred to in paragraph  (a)(viii)
                           are duly  accepted  and such  persons as the relevant
                           Purchaser   nominates  are  appointed  as  additional
                           directors and secretaries of the Companies;

                  (ii)     their registered offices are changed as the 
                           Purchasers require;  and

                  (iii)    the transfers  referred to in paragraph  (a)(i) above
                           (subject  only  to  their  being  duly  stamped)  are
                           approved for registration.

(3)      Upon completion of the matters referred to in subclause (2) above the 
         Purchasers shall:

         (a)      procure the repayment of the Companies Loans by or on behalf 
                  of the Companies and pay the Initial Consideration to the 
                  Seller; and

         (b) deliver to the Seller a duly executed counterpart of the Tax Deed.

(4)      The Purchasers agree that as soon as practicable  following  Completion
         they will  assist the Seller to remove  from the 401K Plan of  Andersen
         Inc the  entitlements  of any  employees of any members of the Seller's
         Group,  with any costs of such removal being borne by the Seller to the
         extent that it has not been completed by the date of Completion.

9.        LOAN ACCOUNTS AND SETTLEMENT OF CASH BALANCES

(1)      Any sums owed at Completion by any member of the Seller's  Group to any
         Company  or vice  versa  in  respect  of  trading  between  them in the
         ordinary  course of business shall be discharged in accordance with the
         terms previously agreed between them.

(2)      It is  acknowledged  by each of the Purchasers  that in preparation for
         the sale of the Companies the Seller has  re-organised  the  Companies'
         banking  arrangements  and  details  of all  these  changes  have  been
         disclosed to them in the Disclosure Letter.

(3)      Within five days from the date of  Completion  the  Purchasers  shall
         deliver to the Seller a bank statement as at the opening of business on
         the  date of  Completion  for  each  bank  account  in the name of each
         Company (the  "Completion  Bank  Statements")  and pay to the Seller as
         additional  consideration for the sale of the Shares an amount equal to
         the  aggregate  of the  cash  balances  shown  on the  Completion  Bank
         Statements. For this purpose, all such cash balances shall be converted
         into sterling from the relevant currency at the prevailing spot rate of
         exchange of that currency as published in the  Financial  Times (London
         edition) the next business day after Completion.
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10.       GUARANTEES

(1)      The Seller shall procure that on or as soon as  reasonably  practicable
         after  Completion  the Companies are released from all  guarantees  and
         indemnities  (if any) given by them in respect of any obligation of any
         member of the Seller's Group.

(2)      The  Purchasers  shall  procure  that  on  or  as  soon  as  reasonably
         practicable  after  Completion  each  member of the  Seller's  Group is
         released from all  guarantees and  indemnities  (if any) given by it in
         respect of any obligation of any of the Companies and pending each such
         member's  release the Purchasers shall indemnify the Seller (for itself
         and as trustee  for each such  member)  against all  liabilities  under
         those guarantees and indemnities.

11.                      PENSIONS

(1)      The parties  shall comply with the  provisions of Schedule 4 applicable
         to  them  ("Schedule")  and  the  Purchasers  shall  procure  that  the
         principal  employer of the  Purchaser's  Scheme  shall  comply with the
         provisions  of this  clause  and such  Schedule  applicable  to it. All
         expressions  used in this  clause  have  the  same  meaning  as in that
         Schedule  except that  "Transfer  Amount"  means the greater of A and B
         where:

         A is the Transfer Amount defined in the Schedule;

         B is the  aggregate  of (a), (b) and (c) below  adjusted in  accordance
with (d) below:

         (a)      The amount which the Transfer  Amount  defined in the Schedule
                  would have been if the unadjusted  Transfer Amount,  excluding
                  the amount referred to in paragraph 7 of the Actuary's Letter,
                  had been calculated using a valuation rate of interest of nine
                  per cent.  per annum,  a rate of general pay  inflation of six
                  per cent. per annum and a market value  adjustment of 3.03 per
                  cent  divided by the net yield on the  FT-Actuaries  All Share
                  Index on the Membership Transfer Date.
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         (b)      The capital value,  calculated on the same basis as the amount
                  in (a) above,  at Membership  Transfer Date of the  Consenting
                  Members'  normal  contributions  to  the  Seller's  Scheme  in
                  accordance  with the Rules for the period up to 31st December,
                  1999.

         (c)      The capital value,  calculated on the same basis as the amount
                  in (a) above,  at Membership  Transfer Date of the  difference
                  between  an  employer's  contribution  rate  for the  relevant
                  Company  of nine  point  five per cent.  and six per cent.  of
                  Salary  in  respect  of each  Consenting  Member  for a period
                  starting on the  Membership  Transfer Date and ending 10 years
                  and 4 months after the date of Completion.

         (d)      The  aggregate  of (a),  (b) and (c)  above  is  increased  or
                  decreased  by  the  Investment   Adjustment  over  the  period
                  starting on the Membership Transfer Date and ending at the end
                  of the day which is three days before the Actual  Payment Date
                  and then  increased  by  interest at the Agreed Rate from (and
                  including)  the day which is 3 days before the Actual  Payment
                  Date  until the end of the day  immediately  before the Actual
                  Payment Date.

(2)      If the Transfer  Amount is not  transferred in full to the  Purchaser's
         Scheme  within one month after the Due Payment  Date the Seller  shall,
         subject to subclauses  (3) and (4) below,  forthwith  upon receipt of a
         written demand from either Purchaser,  pay to the relevant  Purchasers,
         by way of  reduction to the  consideration  for the sale of the Shares,
         the following amount:

         (i)      if some assets have been  transferred from the Seller's Scheme
                  to the  Purchaser's  Scheme  (whether  before  or  after  that
                  written demand is received) - the amount by which the Transfer
                  Amount  (calculated  as at the date on which those assets were
                  transferred)  exceeds the value so transferred  but the excess
                  for this purpose shall:

                  (a)      be the excess  adjusted by the Investment  Adjustment
                           from (and  including) the date of that transfer up to
                           (but  excluding)  the date of  payment  by the Seller
                           pursuant to this sub-paragraph; and
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                  (b)      be reduced  (after the adjustment in (a)) if, despite
                           some   assets   having   been   transferred   to  the
                           Purchaser's Scheme, any benefit remains payable to or
                           in respect of a Consenting  Member under the Seller's
                           Scheme; the reduction will be by the aggregate of the
                           cash equivalents of those benefits.

         (ii)     if no assets have been transferred from the Seller's Scheme to
                  the  Purchaser's  Scheme - the  amount by which  the  Transfer
                  Amount  (calculated as at the date on which payment is made to
                  the relevant Purchasers in accordance with this subclause (2))
                  exceeds the aggregate of the cash  equivalents of the benefits
                  remaining  payable to or in respect of the Consenting  Members
                  under the Seller's  Scheme when payment is made in  accordance
                  with this subclause (2);

         less (in either case):

         (iii)      any amount due from the Purchasers or the relevant Company 
                    to the Seller or the Seller's Scheme under the Schedule; and

         (iv)     any amount, in addition to the amount transferred  referred to
                  in (i)  above,  transferred  from the  Seller's  Scheme to the
                  Purchaser's Scheme before payment under this sub-clause (2) is
                  made adjusted by the  Investment  Adjustment  from the date of
                  transfer to the date of such payment.

         The amount  derived under (i) to (iv) above is referred to below as the
"Shortfall".

(3)      If any of the Transfer  Conditions ceases to be fulfilled or effective,
         the relevant  Purchasers  shall not demand payment under  subclause (2)
         above and the time limit  referred to in  subclause  (2) above will not
         commence,  or (if any of the Transfer  Conditions cease to be fulfilled
         or  effective  after  the  time  limit  has  started  to  run)  will be
         suspended, until all those conditions are again fulfilled or effective.
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(4)      No payment shall be paid by the Seller under subclause (2) above:

         (i)      if the  reason  for the  Transfer  Amount  (or part of it) not
                  having been  transferred to the Purchaser's  Scheme is because
                  of the  continuing  failure  of  the  Purchaser's  Scheme  for
                  whatever  reason  to  accept  the  whole  or any  part  of the
                  Transfer  Amount or if the reason is any other reason  outside
                  the control of the  Seller's  Scheme but, if no payment is due
                  from the  Seller  because  of any such  reason,  payment  will
                  become due (subject to the other provisions of this clause) if
                  and when such reason ceases to exist;

         (ii)     unless the  Purchasers  undertake  in writing to the Seller to
                  pay the Shortfall  forthwith to the Purchaser's  Scheme and to
                  procure that such amount be applied by the Purchaser's  Scheme
                  to provide  benefits for the Consenting  Members in respect of
                  their  Pensionable  Service in the Seller's  Scheme before the
                  Membership  Transfer Date to the extent  required by paragraph
                  3(D) of the Schedule only.

(5)      If payment is made by the Seller in accordance with subclause (2) above
         the amount of that payment will be deducted  from the amount  otherwise
         payable under paragraph 6(A) of the Schedule.

(6) If the Seller pays the Shortfall to the Purchasers then:

         (i)      forthwith  following  the Seller  making  payment  pursuant to
                  subclause  (2)  above the  Purchasers  shall  procure  that an
                  amount  equal to the  Shortfall  shall be  contributed  to the
                  Purchaser's Scheme; and

         (ii)     the  Purchasers  will  procure  that  the  Purchasers  and all
                  members  of the  Purchasers'  Group  will take all  reasonable
                  steps  (including the claiming of any relevant  deduction from
                  profits and any repayment of tax and the obtaining of approval
                  of the  Purchaser's  Scheme as an Exempt  Approved  Scheme) to
                  maximise the Aggregate Tax Benefit;

         (iii)    the  Purchasers  shall within two days after the Aggregate Tax
                  Benefit has been finally determined by the Inland Revenue, pay
                  to the Seller,  by way of adjustment to the  Consideration for
                  the Shares,  an amount  equal to the  Aggregate  Tax  Benefit,
                  increased by interest at the Agreed Rate from (and  including)
                  the date of payment of the Shortfall up to (but excluding) the
                  date of payment by the Purchaser of that excess.
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                  In this subclause:

                  "Tax  Benefit"  means the aggregate of the amount by which the
                  relevant company's liability to pay corporation tax is reduced
                  and the amount of any  repayment of  corporation  tax to which
                  the  relevant  company is  entitled,  which,  in either  case,
                  arises  as a result  of the  contribution  referred  to in (i)
                  above   (including  any  such  reduction  or  right  which  is
                  attributable  to  a  surrender  by  way  of  group  relief  or
                  consortium  relief under sections 402 to 413 of the Income and
                  Corporation  Taxes Act 1988 of a loss which arises as a result
                  of the payment of the contribution); and

                  "Aggregate  Tax  Benefit"  means  the  aggregate  of  any  Tax
                  Benefits  arising to the Purchasers and the Purchasers'  Group
                  in  respect of all  accounting  periods on or before the fifth
                  anniversary of the date of Completion.

(7)      If,  for a  reason  outside  the  Seller's  control,  the  value of the
         aggregate  of the  assets  transferred  by the  Seller's  Scheme to the
         Purchaser's  Scheme  and the  assets  transferred  by the Seller to the
         Purchasers  under this clause (in the case of non-cash  assets based on
         the value of the assets transferred as at the date of transfer) exceeds
         the Transfer Amount, the Purchasers shall,  within one month of such an
         excess  having  been  transferred,  pay  to  the  Seller,  by way of an
         adjustment to the  consideration  payable for the sale of the Shares, a
         sum in cash equal to half of such  excess  adjusted  by the  Investment
         Adjustment  from (and  including) the date of transfer of the excess to
         the Purchaser's Scheme up to (but excluding) the date of payment of the
         excess by the  Purchasers  to the  Seller  provided  that the  Seller's
         Guarantor  shall have  exercised all  reasonable  endeavours to procure
         that no such excess shall arise and provided further that the amount of
         any such excess shall be available to such  Companies as are  employers
         under the Purchaser's  Scheme to fund  contributions  as employer under
         the Purchaser's Scheme notwithstanding the other provisions hereof.

12.                      PROTECTIVE COVENANTS

(1)      The Seller's  Guarantor  covenants  with the Purchasers as trustees for
         themselves  and the Companies  that it shall not and shall procure that
         no member of the Seller's Group shall:
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         (a)      for  a  period  of  12  months  from  Completion  directly  or
                  indirectly carry on any business which is competitive with any
                  of the  businesses  carried on by the  Companies at Completion
                  nor be concerned or interested in any such business; or

         (b)      for a period of 12 months from Completion induce or attempt to
                  induce any supplier of the Companies to cease to supply, or to
                  restrict or vary the terms of supply, to the Companies; or

         (c)      for a period of 12 months from Completion directly solicit the
                  employment of any present employee of the Companies; or

         (d)      at any time after Completion  disclose or divulge to any third
                  party  any  information  of a secret  or  confidential  nature
                  relating to the business or affairs of the  Companies  (except
                  as required by law or any competent  regulatory body) provided
                  that this  shall not apply to any such  information  which has
                  come into the public domain other than as a result of a breach
                  of this agreement by a member of the Seller's Group.

(2)      The  restrictions in subclause (1)(a) above shall not apply (or, as the
         case may be,  shall cease to apply)  insofar and to the extent that any
         member of the Seller's Group after Completion on bona fide arm's length
         terms  acquires  any  company or business or merges with any company or
         business and, as a result of that  transaction,  falls within the terms
         of subclause  (1)(a) above (the  "Relevant  Interest")  if turnover and
         profits  before  interest  and  taxation  attributable  to the Relevant
         Interest each constitute  less than 15 per cent. of aggregate  turnover
         and aggregate  profits before interest and taxation,  respectively,  of
         the companies and  businesses  acquired or merged with, in each case by
         reference  to the  most  recent  audited  financial  statements  of the
         relevant  companies and businesses.  If the Relevant  Interest  exceeds
         that threshold then the Seller shall if requested by a Purchaser  enter
         into bona  fide  negotiations  to sell the  Relevant  Interest  to that
         Purchaser at fair market value.

(3)      For the  purposes of subclause  (1) a member of the  Seller's  Group is
         concerned or  interested in a business if it carries it on as principal
         or agent or if:
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         (a)      it is a partner, director, employee, secondee, consultant or 
                  agent in, of or to any person who carries on the business; or

         (b)      it  has  any  direct  or  indirect   financial   interest  (as
                  shareholder  or  otherwise)  in any person who  carries on the
                  business; or

         (c)      it is a partner, director, employee,  secondee,  consultant or
                  agent in,  of or to any  person  who has a direct or  indirect
                  financial interest (as shareholder or otherwise) in any person
                  who carries on the business,

         disregarding any financial interest of a person in securities which are
         listed on the  London  Stock  Exchange  or  traded  in the  Alternative
         Investment  Market if that person and the Seller's Group are interested
         in  securities  which amount to less than five per cent.  of the issued
         securities of that class and which,  in all  circumstances,  carry less
         than five per cent.  of the  voting  rights (if any)  attaching  to the
         issued securities of that class.

(4)      Each of the  restrictions in each paragraph or subclause above shall be
         enforceable  by the  relevant  Purchaser  independently  of each of the
         others and its  validity  shall not be affected if any of the others is
         invalid;  if any of those  restrictions  is void but  would be valid if
         some part of the restrictions  were deleted the restriction in question
         shall apply with such deletion as may be necessary to make it valid.

(5)      If by  virtue  of any  provision  of  this  agreement  or of any  other
         agreement  or  arrangement  of which this  agreement  forms part,  such
         agreement  or  arrangement  is  subject  to   registration   under  the
         Restrictive  Trade  Practices  Act 1976,  none of the  parties  to such
         agreement  or  arrangement  who carries on  business  within the United
         Kingdom  shall give  effect  to, or  enforce or purport to enforce  the
         agreement or arrangement in respect of any such provision until the day
         after  particulars of the agreement or arrangement  have been furnished
         to the Director General of Fair Trading under section 24 of that Act.

13.      CHANGE OF NAME

(1)      The  Purchasers  shall  procure  that  on  or  as  soon  as  reasonably
         practicable  after Completion and in any event within ten business days
         after  Completion the names of those  Companies  which include the word
         "Graseby"  are  changed  to a name  which  does  not  include  the word
         "Graseby" or any name which is or might be confused  with that name and
         that the  Seller is  provided  with a  certified  copy of the  relevant
         special resolutions and incorporation on change of name certificates or
         the overseas equivalent.
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(2)      The Purchasers  shall be entitled to continue to use the name "Graseby"
         on all  existing  media  (including,  without  limitation,  stationery,
         brochures,   pamphlets,   catalogues,   invoices,  written  orders  and
         receipts,  building  signs  and van and  truck  livery)  of each of the
         Companies for a period of six months from Completion.

(3)      The  Purchasers  shall  further  procure that save in  accordance  with
         subclause (2) above the name  "Graseby"  will not be used by any of the
         Companies or by any member of the Purchasers'  Group and that on expiry
         of the period  referred to in  subclause  (2) above the use of the name
         "Graseby"  by each of the  Companies  or any member of the  Purchasers'
         Group will cease forthwith.

(4)      In so far as any trade or service mark  registrations  or  applications
         for  registration  are held at  Completion  by any  Company in the name
         "Graseby"  (including any trade or service mark  incorporating the name
         "Graseby")  the  Purchasers  shall  procure that any such  registration
         shall be  assigned  to the Seller  free from  encumbrances  (other than
         those existing at Completion) for a nominal  consideration  of (pound)1
         on request.

(5)      In so far as any  Intellectual  Property  Rights  owned by the  Graseby
         Group are used in the business of the Companies on or immediately prior
         to  Completion  then the Seller shall assign or procure the  assignment
         of, at the Seller's cost and expense,  all such  Intellectual  Property
         Rights as are used exclusively in the business of the Companies to such
         of the Companies as the Purchasers may nominate as soon as practicable;
         to the extent any such rights are not used  exclusively in the business
         of the Companies or pending  completion of such  assignments the Seller
         shall grant or procure that the relevant  member of its Group grants to
         the relevant Company a non-exclusive,  royalty free licence to use such
         Intellectual Property Rights as part of the relevant Company's business
         as was carried on at or  immediately  prior to  Completion  and on such
         other  terms  as shall  be  appropriate  to  protect  the  Intellectual
         Property  Rights of the Graseby  Group in those  rights  (both  parties
         acting  reasonably  and  provided no warranty  or other  obligation  in
         respect  of such  Intellectual  Property  Rights  shall be given by the
         Graseby  Group) and the  Purchasers  shall  procure  that the  relevant
         Company shall  indemnify the Seller  against all actions,  proceedings,
         costs,  damages and demands in respect of the relevant Company's use of
         any such Intellectual Property Rights under such licence. To the extent
         that any such licence or  assignment  permits the Companies to continue
         to carry out their business in substantially the same way as carried on
         prior to  Completion,  the  Seller  shall not be liable for breach of a
         Warranty  or a failure  by it to  disclose  any  Company's  use of such
         Intellectual Property Rights.
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(6)      In so far as any Intellectual  Property Rights are owned by any Company
         and  are  used  by  the  Seller's  Group  on or  immediately  prior  to
         Completion,  the relevant Company shall grant to the relevant member of
         the Seller's  Group a  non-exclusive,  royalty free licence to use such
         Intellectual  Property  Rights as part of the  business of the Seller's
         Group as was carried on at or  immediately  prior to Completion  and on
         such other terms as shall be  appropriate  to protect the  Intellectual
         Property  Rights of the Company in those  rights (both  parties  acting
         reasonably  and provided no warranty or other  obligation in respect of
         such  Intellectual  Property  Rights shall be given by the Company) and
         the relevant  member of the Seller's Group shall indemnify the relevant
         Company against all actions,  proceedings,  damages, claims and demands
         in respect of the relevant  member of the Seller's  Group's use of such
         Intellectual Property Rights under such licence.

(7)      Each party (and any Company)  shall be  responsible  at its own expense
         for  procuring  any right to use or  continue  using  any  Intellectual
         Property Rights belonging to any third party after  Completion.  To the
         extent that any such  licence or  assignment  permits the  Companies to
         continue to carry out their business in  substantially  the same way as
         carried  on prior to  Completion,  the  Seller  shall not be liable for
         breach of a Warranty or a failure by it to disclose any  Company's  use
         of such Intellectual Property Rights.

14A.                     GUARANTEE OF THE SELLER'S GUARANTOR

(1)      In  consideration  of the  Purchasers  and  the  Purchasers'  Guarantor
         entering into this agreement (and for other valuable  consideration the
         receipt and sufficiency of which the Seller's Guarantor  acknowledges),
         the Seller's Guarantor guarantees to each of the Purchasers the due and
         punctual  payment of all monies due by the Seller to the Purchasers and
         performance  of all  the  Seller's  other  obligations,  warranties  or
         undertakings  arising  under  this  agreement  and the Tax Deed and the
         Seller's  Guarantor  agrees to  indemnify  the  Purchasers  against all
         losses, costs,  charges,  expenses,  actions,  claims and demands which
         either  Purchaser may suffer  through or arising from any breach by the
         Seller  of its  obligations,  warranties  or  undertakings  under  this
         agreement or the Tax Deed.  The Seller's  Guarantor  shall not be under
         any  obligation  to make any  payment  to either  Purchaser  under this
         subclause  unless and until such  Purchaser has obtained a judgement in
         its favour in respect of the relevant  matter (which cannot be appealed
         against) or the Seller's Guarantor has agreed in writing to the claim.
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(2)      This  guarantee  shall be a  continuing  guarantee  and shall remain in
         force until all the Seller's  obligations  under this agreement and the
         Tax Deed have been performed.

(3)      The  guarantee of the Seller's  Guarantor  shall not be affected by any
         legal limitation  disability or other circumstances  (including for the
         avoidance of doubt any time or  indulgence  granted,  other  variation,
         winding  up or  cessation  of  trade)  relating  to the  Seller  or any
         irregularity,   unenforceability  or  invalidity  of  any  obligations,
         warranties or  undertakings  of the Seller under this  agreement or the
         Tax Deed.

14B.                     GUARANTEE OF THE PURCHASERS' GUARANTOR

(1)      In consideration of the Seller and the Seller's Guarantor entering into
         this agreement (and for other  valuable  consideration  the receipt and
         sufficiency  of which  the  Purchasers'  Guarantor  acknowledges),  the
         Purchasers'  Guarantor  guarantees  to the Seller the due and  punctual
         payment  of all  monies  due  by  the  Purchasers  to  the  Seller  and
         performance of all the  Purchasers'  other  obligations,  warranties or
         undertakings  arising  under  this  agreement  and the Tax Deed and the
         Purchasers'  Guarantor  agrees to  indemnify  the  Seller  against  all
         losses, costs, charges, expenses, actions, claims and demands which the
         Seller may suffer  through or arising from any breach by the Purchasers
         of their  obligations,  warranties or undertakings under this agreement
         or the Tax  Deed.  The  Purchasers'  Guarantor  shall  not be under any
         obligation  to make any  payment  to the Seller  under  this  subclause
         unless and until the Seller has  obtained a judgement  in its favour in
         respect of the relevant  matter (which  cannot be appealed  against) or
         the Purchasers' Guarantor has agreed in writing to the claim.
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(2)      This  guarantee  shall be a  continuing  guarantee  and shall remain in
         force until all the  Purchasers'  obligations  under this agreement and
         the Tax Deed have been performed.

(3)      The guarantee of the Purchasers' Guarantor shall not be affected by any
         legal limitation  disability or other circumstances  (including for the
         avoidance of doubt any time or  indulgence  granted,  other  variation,
         winding up or cessation of trade)  relating to either of the Purchasers
         or any irregularity, unenforceability or invalidity of any obligations,
         warranties  or  undertakings  of either of the  Purchasers  under  this
         agreement or the Tax Deed.

15.       ANNOUNCEMENTS

(1)      None of the parties shall make or permit any person  connected  with it
         to make any  announcement  concerning  this  sale and  purchase  or any
         ancillary  matter  before,  on or  for a  period  of  12  months  after
         Completion  except as required by law or any competent  regulatory body
         or in  communications  in the ordinary course with its investors and/or
         any market analysts or with the written  approval of the other parties,
         such  approval  not to be  unreasonably  withheld or delayed.  No party
         shall  at any  time  make  any  announcement  regarding  this  sale and
         purchase or any ancillary  matter which might reasonably be expected to
         damage the reputation of any of the other parties in any way.

(2)      The Seller and the Purchasers  undertake that they shall not, and shall
         procure  that no  member of the  Seller's  Group or  Purchasers'  Group
         respectively  shall,  at any  time  after  the  date of this  agreement
         divulge or communicate any of the terms of this agreement to any person
         other than to its professional  advisers or with the written consent of
         the  others  or to the  extent  required  by law  or by  the  rules  or
         regulations  of the  London  Stock  Exchange  or any  other  recognised
         investment  exchange  or in  connection  with  obtaining  advice on its
         rights or  obligations  under this  agreement or enforcing or defending
         any claim in respect of the same.

16.                      NOTICES

(1)      Any notice or other  document to be served under this  agreement may be
         delivered by hand or sent by first class post or  facsimile  process to
         the party to be served at its address appearing in this agreement or at
         such other  address  as it may have  notified  to the other  parties in
         accordance with this clause.
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(2) Any notice or document shall be deemed to have been served:

         (a)      if delivered by hand, at the time of delivery; or

         (b)      if  posted,  at 10.00  a.m.  on the  second (or in the case of
                  international  post, the fourth) business day after it was put
                  into the post; or

         (c)      if sent by facsimile process, at the expiration of two hours 
                  after the time of despatch, if despatched before 3.00 p.m. on
                  any business day, and in any other case at 10.00 a.m. on the
                  business day following the date of despatch.

(3)      In proving  service of a notice or document it shall be  sufficient  to
         prove that delivery was made or that the envelope containing the notice
         or document was properly  addressed and posted as a prepaid first class
         letter  or that  the  facsimile  message  was  properly  addressed  and
         despatched as the case may be.

17.                      APPORTIONMENT OF FURTHER PAYMENTS

         Any  amount  to be paid by any party to the  others  under the terms of
         this  agreement  which would  constitute an increase or a reduction (as
         the  case  may  be)  in the  consideration  for  the  Shares  shall  be
         apportioned  amongst the Shares in a manner to be agreed by the parties
         to  this  agreement.  Failing  such  agreement  within  14  days of the
         relevant  payment  being  made,  the  amount of such  payment  shall be
         apportioned  in the same  proportions as the Initial  Consideration  is
         allocated between the Shares under clause 3A.

18.       GENERAL

(1)      Each of the obligations,  Warranties,  indemnities and undertakings set
         out in this agreement  which is not fully  performed at Completion will
         continue in force after Completion.

(2)      Unless  otherwise  expressly  stated all payments to be made under this
         agreement shall be made in sterling to the party to be paid as follows:
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         (a)      to the Seller in immediately available funds to the account of
                  the Seller at:

                  bank:               Barclays Bank Plc
                                      Broadgate Business Centre
                  sort code:          20-77-67
                  account number: 30240869

                  or such other account as the Seller may specify; and

         (b)      to the  Purchasers  in  immediately  available  funds  to such
                  account as the Purchasers may specify.

(3)      Save as  contemplated  in clause 4 and without  prejudice  to any other
         remedy  available  to any party for  breach  of this  agreement  by the
         others,  no  party  may  rescind  this  agreement  at any  time  in any
         circumstances.

(4)      The Seller or either  Purchaser  may,  without the consent of any other
         party to this  agreement,  assign to another  company  in the  Seller's
         Group or the Purchasers'  Group  respectively the benefit of all or any
         of another  party's rights under this  agreement  provided that if such
         assignee leaves the Seller's Group or Purchasers' Group respectively it
         shall immediately before it ceases to be a member of the Seller's Group
         or  Purchasers'  Group assign its rights under this agreement back to a
         member of the Seller's Group or the Purchasers'  Group, as the case may
         be,  failing which such rights shall cease to be  enforceable.  Save as
         provided in this  subclause,  none of the rights or  obligations  under
         this  agreement may be assigned or  transferred  by a party without the
         prior written consent of the Seller,  in the case of an assignment by a
         Purchaser,  or  of  the  relevant  Purchaser(s),  in  the  case  of  an
         assignment by the Seller.  The Seller's  Guarantor and the  Purchasers'
         Guarantor   agree  that  their   guarantees  in  clauses  14A  and  14B
         respectively  shall  continue  to apply in favour of any person to whom
         assignment is permitted under this subclause.

(5)      Each  party  shall  pay  the  costs  and  expenses  incurred  by  it in
         connection with the entering into and completion of this agreement.

(6)      This  agreement  may be executed in  counterparts,  each of which taken
         together shall  constitute one and the same agreement and any party may
         enter into this agreement by executing a counterpart.
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(7)      For a period of 12 months from the date of Completion  the Seller shall
         from time to time forthwith upon reasonable request from the Purchasers
         (at the  Seller's  expense)  do or procure the doing of all acts and/or
         execute or procure the execution of all such  documents for the purpose
         of vesting in the  Purchasers  or the relevant  Company as the relevant
         Purchaser may direct,  any member of the Graseby  Group's title to such
         assets (other than  Intellectual  Property  Rights or real property) as
         are used  exclusively  by any of the  Companies in the operation of its
         business as currently  conducted which the Purchasers  become aware are
         owned by a member of the Graseby  Group.  If any such asset (other than
         Intellectual Property Rights or real property) is also used by a member
         of the  Graseby  Group then the Seller  shall at the  Seller's  expense
         procure that the  Purchasers are granted a  non-exclusive  royalty free
         licence to use such asset.

(8)      If after the date of this  agreement  the Seller  becomes  aware of any
         real property which is owned by a member of the Graseby Group and which
         is occupied by a Company then the Seller will procure that the relevant
         member of the Graseby Group will (at the Seller's expense), transfer to
         that Company,  and the  Purchasers  will procure that such Company will
         take a  transfer  of such  property  for nil  consideration.  The terms
         governing such a transfer shall be equivalent to those terms  contained
         in an agreement  between  Goring Kerr PLC (1) and Goring Kerr Detection
         Limited  (2)  dated  11th  March,  1998  except  that  clause 4 of that
         agreement shall not be included.

19.       WHOLE AGREEMENT

(1)      This  agreement and the  documents  referred to in it contain the whole
         agreement between the parties relating to the transactions contemplated
         by this  agreement and supersede  all previous  agreements  between the
         parties relating to these transactions.

(2)      Each of the  parties  acknowledges  that in agreeing to enter into this
         agreement it has not relied on any representation, warranty, collateral
         contract or other assurance (except those set out in this agreement and
         the  documents  referred  to in it) made by or on  behalf  of any other
         party  before the  signature  of this  agreement.  Each of the  parties
         waives all rights and remedies  which,  but for this  subclause,  might
         otherwise  be  available  to it in respect of any such  representation,
         warranty, collateral contract or other assurance, provided that nothing
         in this subclause shall limit or exclude any liability for fraud.
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20.       GOVERNING LAW

(1) This  agreement  is governed by and shall be construed  in  accordance  with
English law.

(2)      The Purchasers and the Purchasers' Guarantor submit to the jurisdiction
         of the English  courts for all purposes  relating to this agreement and
         irrevocably  appoint  the  Purchasers'  Solicitors  as their  agent for
         service of process.

(3) AS WITNESS the hands of a duly authorised  officer of each of the parties on
the date which appears first on page 1.

SIGNED by                                   )        Alan Thomson
for and on behalf of                        )
GRASEBY LIMITED                             )

SIGNED by                                   )        D. Helm
for and on behalf of                        )
THERMO ENVIRONMENTAL                        )
INSTRUMENTS INC.                            )

SIGNED by                                   )        L. Ribich
for and on behalf of                        )
THERMO SENTRON INC.                         )

SIGNED by                                   )        Alan Thomson
for and on behalf of                        )
SMITHS INDUSTRIES plc                       )

SIGNED by                                   )        D. Helm
for and on behalf of                        )
THERMO ELECTRON                             )
CORPORATION                                 )
Exhibit 2.2

THIS AMENDMENT AGREEMENT (this "Amendment") is made on the 7th day of May, 1998

BETWEEN:

     (1) GRASEBY LIMITED  registered number 894638 whose registered office is at
765 Finchley Road, London NW11 8DS;

     (2) THERMO ENVIRONMENTAL INSTRUMENTS INC. whose principal place of business
is at 8 West Forge Parkway, Franklin, Massachusetts 02038, USA;

     (3) THERMO  SENTRON INC. whose  principal  place of business is at 501 90th
Avenue, NW, Minneapolis, Minnesota 55433, USA;

     (4) SMITHS  INDUSTRIES plc registered number 137013 whose registered office
is at 765 Finchley Road, London NW11 8DS; and

     (5) THERMO ELECTRON  CORPORATION whose principal place of business is at 81
Wyman Street, Waltham, Massachusetts 02254-9046, USA.

WHEREAS:

The parties to this Amendment  have entered into that certain  Agreement for the
sale and purchase of all the issued  share  capitals of Graseby  Allen  Limited,
Graseby  Product  Monitoring  Limited,  Goring Kerr Detection  Limited,  Graseby
Goring Kerr Inc.,  Graseby  Andersen Inc. and part of the share capital of Allen
France SA (the "Agreement").

The parties  originally  contemplated that all regulatory  approvals required by
clause 4(1) of the Agreement would be received prior to 15th May, 1998.

As of the date of this Amendment,  it appears to the parties that such approvals
will not in fact be received by 15th May, 1998.

The parties believe that it is their mutual interests to continue to pursue such
approvals.

IT IS AGREED as follows:-

                          (1)         Clause 4(3) of the Agreement is hereby 
amended and restated as follows:

         Each of the parties shall use reasonable endeavours to procure that the
         conditions  in sub clause  (1) above are  fulfilled  on or before  30th
         June,  1998 and each of the parties agrees to assist in the preparation
         of all necessary filings with,  attending  meetings with or speaking to
         (if necessary) the regulatory authorities referred to in sub clause (1)
         above.

(2) Except as otherwise  provided  herein,  the  Agreement  shall remain in full
force and effect.

(3)      This  Agreement  may be executed in  counterparts,  each of which taken
         together shall  constitute one and the same agreement and any party may
         enter into this Agreement by executing a counterpart.

(4) This  Amendment  is governed by and shall be construed  in  accordance  with
English law.

AS WITNESS the hands of a duly authorised  officer of each of the parties on the
date which appears first above.

SIGNED by                  )                 Alan Thomson
 ........................   )
for and on behalf of       )
GRASEBY LIMITED            )

SIGNED by                  )                 Melissa F. Riordan
for and on behalf of       )
THERMO ENVIRONMENTAL       )
INSTRUMENTS INC.           )

SIGNED by                  )                 Melissa F. Riordan
 ........................   )
for and on behalf of       )
THERMO SENTRON INC.        )

SIGNED by                  )                 Alan Thomson
 ........................   )
for and on behalf of       )
SMITHS INDUSTRIES plc      )

SIGNED by                  )                 Melissa F. Riordan
 .....................      )
for and on behalf of       )
THERMO ELECTRON            )
CORPORATION                )
Exhibit 2.3

                               DATED 9 June, 1998

                                 GRASEBY LIMITED
                      THERMO ENVIRONMENTAL INSTRUMENTS INC.
                               THERMO SENTRON INC.
                              SMITHS INDUSTRIES plc

                                       and

                           THERMO ELECTRON CORPORATION

                  --------------------------------------------

                                    AGREEMENT

                     to further amend the sale and purchase
                            agreement entered into by
                             the above parties dated
                                13th March, 1998
                (as amended by an agreement dated 7th May, 1998)
                  --------------------------------------------
THIS AGREEMENT is made on 9th June, 1998 BETWEEN:

     (1) GRASEBY LIMITED  registered number 894638 whose registered office is at
765 Finchley Road, London NW11 8DS (the "Seller");

     (2) THERMO ENVIRONMENTAL INSTRUMENTS INC. whose principal place of business
is at 8 West Forge Parkway, franklin, Massachusetts 02038, USA 
("Environmental");

     (3) THERMO  SENTRON INC. whose  principal  place of business is at 501 90th
Avenue, NW, Minneapolis, Minnesota 55433, USA ("Sentron");

     (4) SMITHS  INDUSTRIES plc registered number 137013 whose registered office
is at 765 Finchley Road,
         London, NW11 8DS (the "Seller's Guarantor"); and

     (5) THERMO ELECTRON CORPORATION whose principal place of business is at 81
         Wyman Street, Waltham,  Massachusetts 02254-9046, USA (the "Purchasers'
         Guarantor").

WHEREAS:

(A)      The above  parties  entered into a sale and purchase  agreement on 13th
         March, 1998 (the "Original  Agreement") relating to the sale of all the
         issued  share  capitals  of  Allen,  Product  Monitoring,  Goring  Kerr
         Detection,  Goring  Kerr and  Andersen  Inc.  and the  shares  in Allen
         France.  In order to obtain US  Hart-Scott-  Rodino  clearance  for the
         transactions  contemplated in the Original  Agreement,  the parties now
         wish to  exclude  Graseby  Specac  Limited  and the US Specac  business
         carried  on  by  Andersen  Inc.  (together,  "Specac")  from  the  sale
         contemplated in the Original Agreement.

(B)      The Original  Agreement was amended by an agreement between the parties
         dated  7th  May,  1998 to  extend  the  date  for  satisfaction  of the
         condition precedent in clause 4(1)(a) of the Original Agreement.

(C)      Accordingly the parties have agreed to amend the Original Agreement and
         to certain other matters, as set out in this agreement.

IT IS AGREED as follows:

1.       INTERPRETATION

         All  words and  expressions  defined  in or  pursuant  to the  Original
         Agreement shall have the same meaning in this  agreement,  except where
         amended by this agreement.

2.       CHANGES TO ORIGINAL AGREEMENT

     (1) Save as modified by this agreement,  the Original Agreement (as amended
on 7th May, 1998) shall continue to have effect.

     (2) The Original Agreement shall be deemed to be amended,  with effect from
the date of this agreement, as follows:

         (a)      recital (I) shall be deleted and replaced by the following:

                  "(I)     Graseby  Andersen Limited  ("Andersen  Limited") is a
                           private company  limited by shares short  particulars
                           of which are set out in Part F of  Schedule  1 having
                           an authorised  capital of (pound)100 divided into 100
                           ordinary shares of (pound)1 each of which 2 have been
                           issued (the "Andersen Limited Shares")";

         (b)      recital (J) shall be amended by inserting  "Andersen  Limited"
                  after "Goring Kerr " on the second line;

         (c)      recital (K) shall be amended by inserting ", Andersen  Limited
                  Shares" after "Goring Kerr Shares" on the second line;

         (d)      clause 1(1) shall be amended by:

     (1) changing the figure referred to in the definition of "Companies' Loans"
to (pound)6,359,829; and

     (2) changing the figure  referred to in the definition of "Seller's  Loans"
to
                           (pound)2,280,148;

         (e) clause 1(5) shall be amended by deleting  "Graseby  Specac  Limited
and " from paragraph (f);

     (f) clause  2(1)(b)  shall be amended by adding "and the  Andersen  Limited
Shares" after "Andersen Inc. Shares";

         (g)      clause 3A shall be amended by:

     (1)  deleting  "(pound)35,260,319"  on the first line and  replacing  it by
"(pound)35,460,319";

     (2) delete "and" at the end of clause 3A(e) and insert ";and" at the end of
clause 3A(f); and

     (3) adding a new  paragraph (g) as follows:  "(g) for the Andersen  Limited
Shares, the sum of (pound)200,000";

         (h)      clause 3B(1) shall be amended by replacing "(pound)11,244,000"
                  on the first and fourth lines by "(pound)9,546,000";

         (i)      Clause  8(2)(a)(i)  shall be  amended by adding at the end the
                  words "and a duly executed  declaration  of trust in favour of
                  Environmental in respect of the Andersen Limited Shares";

         (j)      clause  8(2)(a)(ii)  shall be amended by adding after "Product
                  Monitoring Shares" the words ", Andersen Limited Shares";

         (k)      clause  8(2)(a)(v)  shall be  amended by adding at the end the
                  words "not already in the possession of the Companies";

         (l)      Part G of Schedule 2 shall be deleted;

         (m)      Part H of  Schedule  2  shall  be  redesignated  as  Part F of
                  Schedule 1 and opposite the word  "Shareholder"  in that Part,
                  the  word  "Graseby  Specac  Limited"  shall  be  deleted  and
                  replaced by "Graseby Limited as to the beneficial interest and
                  Graseby Specac Limited as to the legal interest"; and

         (n) Part B of Schedule 3 shall be amended by:

     (1) deleting the reference  "(Shares with Graseby Specac Limited)" from the
end of entry for Legal Owner for the Atlanta property (number (13)) on page 43;

     (2) deleting the entry for the Orpington  Property (number (19)) on page 45
and replacing it as follows:

     "(19)  Description:  Part  Ground  Floor and Part Top Floor,  Cray  Avenue,
Orpington (Title No: SGL579547)

     Date of and parties of Graseby  agreement  for lease:  June,  1998  between
Graseby Limited (1) and Andersen Limited (2)

     Legal and Beneficial  owner of interest under agreement for lease:  Graseby
Andersen Limited

                          Term: a maximum of 6 months from Completion

                                    Present rent:             (pound)2,250 pcm

                                    Next rent review:Not applicable

                                    Present use:              Factory/offices";

     (3) deleting all reference to the Newmarket  property at entry (20) on page
45.

(3)      Any references in the Original  Agreement to "this  agreement" shall be
         construed as  references  to the  Original  Agreement as amended by the
         amendment agreement dated 7th May, 1998 and by this agreement.

(4)      The Purchasers  acknowledge that the Seller has taken or procured to be
         taken the following steps to exclude Specac from the sale  contemplated
         by the Original Agreement:

         (a)      by an agreement  dated 8th June,  1998  Andersen Inc. sold the
                  beneficial  interest  in all  its  shares  in  Graseby  Specac
                  Limited  to  the  Seller  for   (pound)5,984,911  to  be  left
                  outstanding on inter-company  loan account and  simultaneously
                  declared  that it held the legal  interest  in such  shares on
                  trust for the Seller;

         (b)      by an agreement  dated 9th June,  1998 Graseby  Specac Limited
                  sold the beneficial interest in the Andersen Limited Shares to
                  the  Seller  for  (pound)200,000  to be  left  outstanding  on
                  inter-company loan account and simultaneously declared that it
                  held the  legal  interest  in such  shares  on  trust  for the
                  Seller; and

         (c)      by an agreement dated 9th June, 1998 Andersen Inc. sold its US
                  Specac business to Specac Inc. (a member of the Graseby Group)
                  for (pound)79,000 to be left outstanding on inter-company loan
                  account.

(5)      The  Purchasers  acknowledge  their consent (for the purposes of clause
         5(1) of the Original  Agreement) to the taking of the steps referred to
         in  subclause  (4) and that  copies of the  agreements  referred  to in
         subclause (4) have been disclosed to them by the Seller. The Purchasers
         further  agree that they shall not be able to make any claim  under the
         Warranties or other terms of the Original Agreement (if applicable) due
         to the transactions contemplated in those agreements occurring.

(6)      The parties  acknowledge that the condition precedent in clause 4(1)(b)
         of the Original Agreement has been satisfied and that Completion of the
         Original  Agreement  shall take place on Friday 12th June,  1998 if (i)
         the  US  Federal  Trade  Commission  or the US  Department  of  Justice
         provides unconditional clearance in respect of the sale contemplated in
         the  Original  Agreement  as  amended  by this  agreement  or (ii)  all
         appropriate  waiting  periods  and any other  time  periods  (including
         extensions   thereto)   under   the  US   Hart-Scott-Rodino   Antitrust
         Improvements  Act 1976 (as amended) and the regulations made thereunder
         have  expired,  lapsed  or  been  terminated  in  respect  of the  sale
         contemplated in the Original Agreement as amended by this agreement, in
         each case on or before  Thursday 11th June, 1998 ((i) and (ii) together
         "Clearance")  . If  Clearance  is not  received  on or before such time
         Completion  shall take place within four  business  days of the date of
         actual Clearance.

(7)      At  Completion  the Tax Deed to be  entered  into by the Seller and the
         Purchasers shall,  notwithstanding  anything  contained in the Original
         Agreement,  be in the form appended to this agreement,  instead of that
         agreed by the parties on 13th March, 1998.

3.       NON-OBJECTION

         The  Purchasers  undertake  to the  Seller  not to submit to the United
         States Department of Justice, the European Commission or any applicable
         national competition or regulatory authority any complaint or objection
         to the sale of Specac by the Seller,  irrespective  of the  identity of
         the  purchaser  of  Specac,  provided  that this will not  prevent  the
         Purchasers  complying with any obligations with regard to the provision
         of  information  or  otherwise  under the  Hart-Scott-Rodino  Antitrust
         Improvements  Act of 1976,  the EC Merger  Control  Regulation,  or any
         other  applicable  law or  regulation.  When  asked by any of the above
         regulatory  authorities  to  comply  with any  obligations  to  provide
         information, the Purchasers shall inform the Seller of this fact unless
         this  constitutes  a  breach  of  the  Purchasers'   obligations  under
         applicable law or regulations.

4.       INTERIM TRANSITIONAL ARRANGEMENTS

(1)      The Purchasers shall procure that  post-Completion  Andersen Inc. shall
         provide  certain  limited  services to Graseby  Specac  Limited  and/or
         Specac Inc. and the Seller shall  procure that Graseby  Specac  Limited
         shall provide certain limited services to Graseby Andersen Limited, all
         such services to be supplied as a temporary  measure in accordance with
         the  principal  terms  and  conditions  set out in  Schedule  1 to this
         agreement.

(2)      If any  obligation or liability  shall arise on Andersen Inc. to make a
         payment  of US  Taxation  to a  Taxation  Authority  in respect or as a
         result of any  transfer  or sale of all the  issued  share  capital  of
         Graseby  Specac  Limited  from  Andersen  Inc.  to  the  Seller,   such
         obligation  or  liability  shall be shared  as to the first  US$500,000
         equally  between the  Purchasers  on the one hand and the Seller on the
         other  hand  and  thereafter  (in  the  event  the  liability   exceeds
         US$500,000)  shall be borne by the Seller alone.  Any payment due under
         this sub-clause  shall be made within 7 days of the amount becoming due
         to a  Taxation  Authority  and  shall  operate  to reduce  the  Initial
         Consideration  for the  Andersen  Inc.  Shares  by the  amount  of such
         payment.

(3)      For  the  purposes  of  this  clause  the  expressions  "Taxation"  and
         "Taxation Authority" shall have the same meaning as they bear under the
         Tax Deed.

5.       EMPLOYEES

         The Seller and  Environmental  agree to use their  best  endeavours  to
procure that:

         (a)      Graseby Specac Limited, Andersen Inc. and Specac Inc. agree
                  with M Cruickshank and A Bibby that:

                  (i)      to the  extent  that  they are  employed  by  Graseby
                           Specac  Limited and  seconded to Andersen  Inc.,  the
                           terms  and  conditions  of  their   secondment   will
                           transfer  to Specac Inc on broadly  equivalent  terms
                           and  conditions as those enjoyed by them  immediately
                           prior to Completion; and

                  (ii)     to the  extent  that they are  employed  by  Andersen
                           Inc.,  all necessary  steps will be taken to transfer
                           their employment to Specac Inc. on broadly equivalent
                           terms  and   conditions  as  those  enjoyed  by  them
                           immediately prior to Completion; and

     (b) the employment of P Galloway is transferred at Completion from Andersen
Inc. to Specac Inc. on terms and conditions  overall equivalent to those enjoyed
by her immediately prior to Completion.

6.        CONFIDENTIAL INFORMATION

(1)      "Information"  means  information of whatever nature relating to Specac
         supplied to the  Purchasers,  Purchasers'  Guarantor or the Purchaser's
         advisers by or on behalf of the Seller in writing,  orally or otherwise
         and includes any information  obtained by the  Purchasers,  Purchasers'
         Guarantor or the Purchasers'  advisers,  in writing or orally,  through
         discussions with the management,  employees and advisers of the Seller,
         together  with any reports,  analyses,  compilations,  studies or other
         documents  prepared by the  Purchasers or on their behalf which contain
         or otherwise reflect such information.

(2)      The  Purchasers  undertake to the Seller to keep strictly  confidential
         all  Information  relating to Specac.  The Purchasers  will not use the
         Information in any way that could be directly or indirectly detrimental
         to the Seller or Specac or so as to procure  any  commercial  advantage
         over the Seller or the Specac business.

(3)      The Purchasers  shall use all their  reasonable  endeavours to promptly
         return to the Seller or  destroy  all  copies of  Information  in their
         possession or control relating to Specac without keeping any copies and
         deliver to the Seller or destroy all notes (and any copies) prepared by
         them (and by any person to whom  disclosure  has been made) and use all
         their reasonable  endeavours to destroy or expunge all Information from
         any computer, word processor or other device containing it.

(4) The Purchasers further acknowledge and confirm to the Seller that:

         (a)      remedies at law may be inadequate to protect  against a breach
                  of this clause and hereby  agree in  advance,  in the event of
                  any such breach on their part,  not to oppose the  granting of
                  injunctive  relief,  specific  performance or other  equitable
                  relief in favour of the Seller without proof of actual damage;

         (b)      no  failure  or  delay  in  exercising  any  right,  power  or
                  privilege  under this clause  will  operate as a waiver of it,
                  nor will any single or partial  exercise  of it  preclude  any
                  further  exercise  or the  exercise  of any  right,  power  or
                  privilege  under this clause or otherwise.  No modification to
                  this clause or any waiver  granted by the Seller in respect of
                  any action taken by the  Purchasers or their advisers shall be
                  effective unless agreed in writing by the Seller; and

         (3)      the  provisions of this clause shall be severable in the event
                  that  any of the  provisions  hereof  are  held by a court  of
                  competent  jurisdiction  to  be  invalid,  void  or  otherwise
                  unenforceable,  and  the  remaining  provisions  shall  remain
                  enforceable to the fullest extent permitted by law.

7A.                      GUARANTEE OF THE SELLER'S GUARANTOR

         The  Seller's  Guarantor  confirms to each of the  Purchasers  that the
         guarantee  given by the  Seller's  Guarantor  under  clause  14A of the
         Original Agreement shall remain in effect  notwithstanding  the changes
         made by the agreement dated 7th May, 1998 and this agreement.

7B.                      GUARANTEE OF THE PURCHASERS' GUARANTOR

         The  Purchasers'  Guarantor  confirms to the Seller that the  guarantee
         given by the  Purchasers'  Guarantor  under  clause 14B of the Original
         Agreement  shall remain in effect  notwithstanding  the changes made by
         the agreement dated 7th May, 1998 and this agreement.

8.                       SEC FINANCIAL STATEMENTS

         The Seller  acknowledges that the Purchasers will be obliged to prepare
         and file  with the U.S.  Securities  and  Exchange  Commission  certain
         financial  statements ("SEC Financial  Statements") with respect to one
         or more of the  Companies,  and that, in  accordance  with UK generally
         accepted  accounting  principles  as  applied  by  the  Seller  to  the
         Companies,  not all of the  information  necessary  to prepare such SEC
         Financial   Statements  in  accordance   with  US  generally   accepted
         accounting  principles  is  contained  in the books and  records of the
         Companies.  Accordingly,  the Seller agrees (i) to co-operate  with the
         Purchasers  and to provide the  Purchasers  with access to the Seller's
         own books and records;  and (ii) to use its  reasonable  endeavours  to
         procure that the Seller's  Accountants  co-operate with the Purchasers,
         including providing access to the Seller's Accountants' work papers, in
         each such case, to the extent  reasonably  necessary  (and only to such
         extent) for the  Purchasers to prepare such SEC  Financial  Statements.
         Such  co-operation  and access shall be provided to the  Purchasers  or
         their accountants during normal working hours at the Seller's principal
         places of business  or at any  location  (including  the offices of the
         Seller's Accountants) where such books and records are maintained.  The
         Purchasers may reasonably  require that the Seller (or they  themselves
         with the prior consent of the Seller) make copies of any such books and
         records  at the  Purchasers'  cost;  provided,  however,  that any such
         copying  shall  be  done  in  such  manner  so as not  to  unreasonably
         interfere  with  the  normal  conduct  of the  Seller's  business.  The
         Purchasers  undertake to the Seller (save as required by applicable law
         or  regulation  and  provided  the  same  is not in the  public  domain
         otherwise than as a result of a breach of this clause) to keep strictly
         confidential all information  obtained  pursuant to this clause and not
         to use any such  information  in any way  that  could  be  directly  or
         indirectly  detrimental to the Seller or Specac or so as to procure any
         commercial  advantage  over the  Seller  or the  Specac  business.  The
         Purchasers further agree that the provisions of clause 6(4) shall apply
         mutatis mutandis to this clause.

9.        GENERAL

(1)      This  agreement  may be executed in  counterparts,  each of which taken
         together shall  constitute one and the same agreement and any party may
         enter into this agreement by executing a counterpart.

(2)      In the event of any  inconsistency  between  the terms of the  Original
         Agreement and the terms of this agreement,  the terms of this agreement
         shall prevail.

(3)      The  provisions  of  clause  15,  16,  18,  19 and  20 of the  Original
         Agreement  shall  apply  to  this  agreement  mutatis  mutandis  as  if
         references in the Original Agreement were references to this agreement.

(4)      Clause 2(2)(i) contemplates that the Purchasers will be provided with a
         duly executed  stock  transfer form in respect of the Andersen  Limited
         Shares (the "Form"). The Seller shall use all reasonable  endeavours to
         procure  that  the  Purchasers  are  provided  with the Form as soon as
         possible after Completion but the Seller undertakes to provide the Form
         to the  Purchasers  within 6 months of Completion in any event.  If the
         Purchasers  become liable to pay a penalty or fine or similar charge to
         the Inland Revenue as a result of their not having been provided within
         28 days of  Completion  with the Form the Seller  shall  reimburse  the
         Purchasers  the same  amount as such  penalty,  fine or similar  charge
         (less the amount of stamp duty comprised therein).
AS WITNESS the hands of a duly authorised  officer of each of the parties on the
date which appears first on page 1.

SIGNED by                                   )        Alan Thomson
for and on behalf of                        )
GRASEBY LIMITED   )

SIGNED by                                   )        L. J. Ribich
for and on behalf of                        )
THERMO ENVIRONMENTAL                        )
INSTRUMENTS INC.                            )

SIGNED by                                   )        L. J. Ribich
for and on behalf of                        )
THERMO SENTRON INC.                         )

SIGNED by                                   )        Alan Thomson
for and on behalf of                        )
SMITHS INDUSTRIES plc                       )

SIGNED by                                   )        L. J. Ribich
for and on behalf of                        )
THERMO ELECTRON                             )
CORPORATION                                 )
Exhibit 10

                 THE SECURITIES REPRESENTED HEREBY HAVE NOT BEEN
                 REGISTERED UNDER THE SECURITIES ACT OF 1933, AS
                 AMENDED (THE "ACT"). THESE SECURITIES HAVE BEEN
                 ACQUIRED FOR INVESTMENT, AND NOT WITH A VIEW TO
              DISTRIBUTION OR RESALE, AND MAY NOT BE SOLD, PLEDGED,
              MORTGAGED, HYPOTHECATED OR OTHERWISE TRANSFERRED (1)
              WITHOUT AN EFFECTIVE REGISTRATION STATEMENT UNDER THE
                 ACT COVERING THESE SECURITIES OR (2) UNLESS AN
                    EXEMPTION FROM REGISTRATION IS AVAILABLE.

                              THERMO SENTRON INC.

                      Promissory Note Due December 15, 1998
                             Minneapolis, Minnesota

June 12, 1998

         For value received,  Thermo Sentron Inc., a Delaware  corporation  (the
"Company"),  hereby promises to pay to Thermo Electron Corporation  (hereinafter
referred to as the  "Payee"),  or registered  assigns,  on December 15, 1998, as
described   below,   the   principal   sum   of   twenty-one   million   dollars
($21,000,000.00)  or such part thereof as then remains  unpaid,  to pay interest
from the date hereof on the whole amount of said  principal sum  remaining  from
time to time  unpaid  at a rate per  annum  equal to the rate of the  Commercial
Paper Composite Rate for 90-day  maturities as reported by Merrill Lynch Capital
Markets,  as an average of the last five business  days of the Company's  latest
fiscal quarter then ended, plus twenty-five (25) basis points,  which rate shall
be adjusted on the first  business day of each fiscal quarter of the Company and
shall be in effect for the entirety of such fiscal quarter,  such interest to be
payable in arrears on the first day of each fiscal quarter of the Company during
the term set  forth  herein,  until the whole  amount  of the  principal  hereof
remaining  unpaid  shall  become due and  payable,  and to pay  interest  on all
overdue principal and interest at a rate per annum equal to the rate of interest
announced  from time to time by  BankBoston,  N.A. at its head office in Boston,
Massachusetts  as its "base  rate " plus one  percent  (1%).  Principal  and all
accrued but unpaid interest shall be repaid on December 15, 1998.  Principal and
interest  shall be payable in lawful money of the United  States of America,  in
immediately  available  funds,  at the principal  office of the Payee or at such
other place as the legal  holder may  designate  from time to time in writing to
the Company. Interest shall be computed on an actual 360-day basis.

         This Note may be prepaid at any time or from time to time,  in whole or
in part, without any premium or penalty.  All prepayments shall be applied first
to accrued interest and then to principal.

         The then unpaid principal amount of, and interest  outstanding on, this
Note shall be and become  immediately  due and payable without notice or demand,
at the option of the holder hereof,  upon the occurrence of any of the following
events:

     (a) the failure of the Company to pay any amount due  hereunder  within ten
(10) days of the date when due;

                  (b)  any   representation,   warranty  or  statement  made  or
furnished  to the  Payee by the  Company  in  connection  with  this Note or the
transaction from which it arises shall prove to have been false or misleading in
any material respect as of the date when made or furnished;

                  (c) the failure of the Company to pay its debts as they become
due, the insolvency of the Company,  the filing by or against the Company of any
petition under the U.S.  Bankruptcy Code (or the filing of any similar  petition
under the insolvency law of any  jurisdiction),  or the making by the Company of
an assignment or trust mortgage for the benefit of creditors or the  appointment
of a receiver,  custodian or similar agent with respect to, or the taking by any
such person of possession of, any property of the Company;

                  (d) the sale by the Company of all or substantially all of
its assets;

                  (e) the merger or  consolidation  of the Company  with or into
any other corporation in a transaction in which the Company is not the surviving
entity;

                  (f) the issuance of any writ of attachment, by trustee process
or otherwise,  or any restraining  order or injunction not removed,  repealed or
dismissed  within thirty (30) days of issuance,  against or affecting the person
or property of the Company or any  liability or obligation of the Company to the
holder hereof; and

                  (g) the suspension of the transaction of the usual business of
the Company.

         Upon surrender of this Note for transfer or exchange, a new Note or new
Notes of the same tenor  dated the date to which  interest  has been paid on the
surrendered  Note and in an  aggregate  principal  amount  equal  to the  unpaid
principal amount of the Note so surrendered will be issued to, and registered in
the name of, the transferee or transferees.  The Company may treat the person in
whose  name this Note is  registered  as the owner  hereof  for the  purpose  of
receiving payment and for all other purposes.

         In case any payment herein provided for shall not be paid when due, the
Company further promises to pay all cost of collection, including all reasonable
attorneys' fees.

         No delay or omission on the part of the Payee in  exercising  any right
hereunder  shall  operate as a waiver of such right or of any other right of the
Payee,  nor shall any delay,  omission or waiver on any one occasion be deemed a
bar to or waiver  of the same or any other  right on any  future  occasion.  The
Company hereby waives presentment, demand, notice of prepayment, protest and all
other  demands  and  notices  in  connection  with  the  delivery,   acceptance,
performance, default or enforcement of this Note. The undersigned hereby assents
to any  indulgence  and any  extension  of time for payment of any  indebtedness
evidenced hereby granted or permitted by the Payee.

         This Note shall be governed by and  construed in accordance  with,  the
laws of the Commonwealth of Massachusetts  and shall have the effect of a sealed
instrument.

                                              THERMO SENTRON INC.

                                              By:/s/ Lewis J. Ribich
                                              Title:   President

[Corporate Seal]

Attest:

/s/ Carl F. Barnes