(1980, Chevy Chase, Jane Seymour)

A private eye is reincarnated as a dog in order to solve his own murder. In an interview Chevy Chase claimed in an interview this was his worst film. There are plenty of contenders for his worst film but I think this has the edge. The movie itself is something of a compromise. Benji, who plays the dog, was not allowed to travel to London for filming, nor it seems did Chase cross the Atlantic, so their scenes were shot in Montreal and Paris, with inserts from London. In particular the opening scenes have a white Mini simultaneously careering round London and a film set in Montreal, with Chase and his stunt double wearing matching overcoats and hats and sporting red umbrellas.
Seen in heavy rain in London are a London Transport Red Arrow AEC Merlin followed by an AEC Routemaster:

The first Canadian footage (also apparently in heavy rain) features two red 'London' buses; the nearer is a former RLH class AEC Regent III/Weymann, the second is apparently a Bristol Lodekka, of which more in a moment:

There appear to be two three RLHs involved in the movie, but that seems far-fetched. The RLH Bus Info Centre has this as RLH8 (KYY508), although at no time in this movie does it carry that registration. The first registration plate we see is LUC456N, which would be a 1974 or 1975 plate, way too new for an RLH! It's seen more clearly as Chase fails to board it, and then accepts a lift in the aforementioned Mini.

Back in London, AEC Routemasters are pounding the streets, the second accompanied by two Duple coaches and the third by a DMS class Daimler Fleetline:


More views of 'LUC456N':

Here's a distant look at the Lodekka I mentioned:

This view of an RLH shows registration AFT154, and I'm not convinced it's the same RLH as we've already seen, unless the film makers took the trouble to change the adverts as well as the registration plate:

Here's the other set again:

Back in London a Routemaster follows an MD-class Scania Metropolitan:

One more RLH shot, this time 1976 or 1977 registration JPC248R……..I give up…