The Absent Minded Professor wrote:
Can anyone help?

Old Ordnance Survey maps, and old bus maps (through the excellent
Mike Harris website) are easy to get hold of, but can anyone suggest
a bookshop that sells old London A-Zs?

You could try the bookstore at the Buckinghamshire Railway Centre @
Quainton Road - I was in there a while back and they're packed with
lots of old railway-related merchandise, some of which appeared to be
A-Zs.