It's surprising to see so many buildings as historic=manor - I would have thought the whole of the Bourne area would have come under just one.

In any case here, either this one or the one at West St x Manor Lane is a fair candidate to be that one building, just by the street name. 

Historic England doesn't specify 91 West Street as a manor house, and it would be too late to be one unless it's been wholly rebuilt (always possible) https://historicengland.org.uk/listing/the-list/list-entry/1243329?section=official-list-entry

The one at this note is consistently shown on the historic OS maps as a hospital for infectious diseases - again, that doesn't mean it's not a manor, but it's a bit of a surprise that it's not named as such: https://maps.nls.uk/view/101591282 