Piccadilly
(1929, Anna May Wong)
The film's opening credits have views of several London General doubledeckers; routes 4, 44 and 14 are glimpsed, also 51.
The bus stop outside the theatre is clearly seen, listing routes 6, 9, 13, 44, 51 and 60.
Anna May Wong's character takes a trip on a bus - it's not seen from the outside, but the interior is seen.