(1948, Terry-Thomas)

“About 20 minutes in, the scene with the market barrow has (in the background) a half-cab coach, followed by a Green Line TF (rare) and 3 STLs which pass in both directions” (thanks Colin Read). The TF class was based on the then-revolutionary Leyland Tiger FEC, an underfloor engined variant of the Tiger. The coach is from Western Scottish:

It's passed by the TF:

…then we see the STLs: