(1968, Horst Tappert, Uschi Glas)

Gratuitous nudity, an attempted drowning and a disfigured man in a gorilla suit - a German crime thriller set in London.
Establishing shots of London Transport RTs, RTLs and an RM:

….but more unusual is a passing XA class Leyland Atlantean/Park Royal:

These stars in a car appear menaced by a back projected RM on route 11 for some distance: