(1965, Dan Duryea, Patricia Owens, Terence Cooper)

One of those 'man gets on one London bus and gets off another identical one' sequences early in the movie.
He gets on RTW452 (LLU942)…..

….and by the time he gets off, it's metamorphosed into RTW489 (LLU979):

This was filmed not long before London Transport began withdrawing the RTWs.