(1969, Peter O'Toole, Petula Clarke)

Musical version of the story casts O'Toole somewhat against type as the eponymous schoolmaster.
He's seen running to catch what appears to be former King Alfred OU9286, a 1931 Dennis 30cwt now preserved by the Friends of King Alfred, under a fake numberplate:


This is all we see of London General S454 (XL8962), a 1922 AEC S-type: