text: I've checked these again:
  
  1) the "London Orbital X miles" sign around the old M10 junction clearly isn't referring to it by name.  I've never seen signage on the M25 for "London Oribital", only the ref and destinations on it (e.g. Heathrow that way, Gatwick this).  It doesn't appear at OS Locator either.  I've never seen anything that could be construed as a road name on the M25 itself.  I've moved it to "description".
  
  2) I've moved e.g. "name=J 21 K" to carriageway_ref as suggested here.
  
  3) I've move "St Albans Bypass" to a "description" tag as well.  It doesn't appear on the road anywhere as a name, and doesn't appear at OS Locator either.
  
  People who want to extract obscure road descriptions can still do so, but people who want road names (or no name where there really is no name) will no longer be confused.