(1939 documentary)

A promotional film looking at London Film Productions' studios at Denham. Seen among employees arriving at work is Blue Belle of London 28 (AGX455), a 1933 AEC Regal with an observation coach body built by London Lorries/Beadle. There's a Red and White coach in background; Richard Smith comments, “I think the coach in the background could be WO6570, a 1932 Albion 28 (image attached). Giveaway may be the distinctive destination box and the very angled windscreen. The R&W on top was removed in later years.”
This would be Red and White 187, new in 1932 with Mumford body.
Red and White acquired Blue Belle Coaching Services in 1937:

If you have an interest in the Red and White group, I recommend Richard's pages at
Bus Fleets of the Red and White Group