The red liveried 'Town and District' fleet comprises a number of Eastern National Bristol KSW5G/Eastern Coachworks: 2359(VNO857 - fleet number 7143 visible in the film), 2367 (VNO871), 2371 (VNO876), 2615 (WNO476), VNO862, VNO866 (thanks Steven Oliver, Stephen Osman and Vic Gackowski)
"According to the PSV Circle fleet history, Eastern National Bristol KSW5Gs 2359 (VNO857), 2367 (VNO862), 2371 (VNO866) and 2376 (WNO476) were all used in 'On the Buses' some time between February and June 1971, were resold and then bought back in February 1972 to use in 'Mutiny on the Buses'. One (or possibly two) I believe went to the USA, and I also think I'm right in saying 2359 is preserved
in the UK." (thanks Chris Stewart)
Paul Burton, who is compiling a website describing the history of Elstree Studios, believes the bus station scenes in the 'On The Buses' films to have been shot at Elstree's Studio Five. Other bus scenes were shot around Elstree and Borehamwood.
In the film VNO857 demolishes a telephone box and a bus stop while on service 13. There is a scene at London Transport's Chiswick works featuring AEC Routemaster RM200 (VLT200) with WH depot plate on the skidpan. In the background during this scene are a number of other London Transport buses, including RTs, RMs, RFs and SMs.
Part of the sequence has Inspector Blakey hanging off the open rear platform (interesting comparison to the stuntwork in 'Speed')
A clue to the main filming location can be seen here, as two RTs sneak into shot, one in Country green.
In the final scene a London Country AEC Regal RF passes, but before that Graeme Selway gleefully notes that "Stan is seen driving WNO476 in the garage towards the front entrance, but when it emerges on to the forecourt, it's magically become VNO857!" Methinks the director was as distracted as Stan.....