(1949, Donald Houston, Moira Lister, Alec Guinness)

Two Welsh miners visit London: A scene in Fleet Street features two RTs and two STLs. One of the miners attempts to board an RTL carrying a harp (!), later an LT is glimpsed outside Wembley Stadium. (thanks Colin Read).
The street footage is a mixture of studio talk with back projection….

……with location shooting:

The only STL identifiable is STL230 (AGX571), a 1933 example:

The attempt to board RTL118 (KGK782) with a harp is successful:

An AEC RT, and glimpsed coaches:

Further along the road, our heroes try and fail to flag down a passing coach - it's 1948 AEC Regal III/Strachan SMY254, operated by Wright Brothers of Hanwell, which also appeared in Passport to Pimlico.