(2004, Daniel Radcliffe)

Features 'The Knight Bus' - this magical triple decker bus is represented in the movie by a modified AEC Regent III RT.

Lettering inside shows it carrying 9 passengers, that is, H3/3/3R rather than the usual H30/36R:

A warning inside the lower deck also warns passengers that 'beds will slide when bus is in motion'!

There is no registration plate, but London Omnibus Traction Society identifies three RTs used in filming: Weymann-bodied RT2240 (KGU169) and RT4497 (OLD717), and Park Royal-bodied RT3882 (LLU681). 'Buses' magazine September 2003 reported one triple deck body was mounted on a modified Dennis Javelin coach chassis. Perhaps that's the reason for the front modifications seen either side of the radiator:

As the Knight Bus careers around London's streets it passes two Routemasters (or perhaps the same one twice?) and a Dennis Dart:

….but the highlight is a confrontation with a pair of Sullivan Buses Leyland Titans, T85 (CUV85V) and T914 (A914SYE):

…which the Knightbus proceeds to squeeze between: