(1972, Christopher Lee, Peter Cushing, Diana Dors)

The first and only movie by Christopher Lee's own Charlemagne production company, with many recruits from Hammer Films.
This curious horror film has an early scene with a group of school children aboard a coach, prominent among whom is a 12 year old Gwyneth Strong, better known nowadays from the BBC comedy 'Only Fools and Horses'. The coach is BMK341A, an AEC Reliance/Harrington from Jack Crump's Denham Coaches fleet at Pinewood. Externally it is only briefly seen from behind, but there are good interior shots:

We see enough of this AEC Routemaster to identify it as an RML: