Keep It Clean
(1956, Tonia Bern, Ronald Shiner)
Opens with some footage of London streets and London Transport buses: RTL1024 (LLU778) on 36A, RT480(HLX297):
RT3387 (LYR606), and the very much older ST2 (GO7154):
Bob Wingrove (whose screencaps these are) also found a distant Bedford OB and AEC RF:
This appears to be a Bristol K/Eastern Coachworks - was it on hire to London Transport?