(1958, Alec Guinness)

The first five minutes feature London Transport Leyland Titans RTW483 (LLU973) and RTW487 (LLU977) on route 31, in fact in the initial sequence one morphs into the other, but there's a third bus seen as well:

There's an AEC RT, RT4704 (NXP989) blinded for route 88:

..and distant RTWs confusing the continuity:

…but this is again RTW483:

At the end of the movie two RT family buses are seen riverside:

(thanks Colin Read)