The Plank (1967, Eric Sykes, Tommy Cooper et al)

Wonderful silent comedy apparently filmed in the Kingston/Barnes area of London.
Features Roy Castle having a smelly encounter with a refuse truck, then boarding then-new AEC Routemaster RML2296(CUV296C). Note the recruiting advert on the side of the bus:

Passengers and conductor jump off the bus complaining about the smell:

Sadly this scene didn't make it into the 1979 remake. (Thanks Colin Read)