The AEC Routemaster is a front-engined double-decker bus that was designed by London Transport and built by the Associated Equipment Company (AEC) and Park Royal Vehicles. The first prototype was completed in September 1954 and the last one was delivered in 1968. The layout of the vehicle was conventional for the time, with a half-cab, front-mounted engine and open rear platform, although the coach version was fitted with rear platform doors. Forward entrance vehicles with platform doors were also produced as was a unique front-entrance prototype with the engine mounted transversely at the rear.

A double-decker bus or double-deck bus is a bus that has two storeys or decks. Double-deckers are primarily for commuter transport, but open-top models are used as sight-seeing buses for tourists, and there are coaches too for long-distance travel. They appear in many places around the world but are presently most commonly used as mass transport in cities of Britain and Ireland, in Hong Kong, and in Singapore.