A Canterbury Tale
(1944, Eric Portman, Sheila Sim)
Herein we see East Kent BJG281, a then-new utility-bodied Guy Arab II. Immediately before this either this or a similar vehicle is glimpsed from a train window. (thanks Colin Read)
There is also a scene at a bus terminus in Chilham in Kent, the bus is seen only from the inside, behind the driver, but the conductress is seen changing the destination blind):
We can only wish this very distant view of what appears to be an East Kent Dennis Lancet were a bit closer: