1955 second prototype AEC RM Type ‘Routemaster’ Bus No.RM2 of London Transport in London Country green livery at the London Transport Acton Depot Museum, 25 September 2021. This bus was one of four prototype Routemasters produced in 1954-57 (one being an experimental RMC Green Line coach) and was put to work in 1957 on Country Area services, hence the green livery. In 1958 it was repainted red and transferred to Central Area services. In 1959 it was used for driver training.

The Routemasters were designed by AAM Durrant, C Curtis and D Scott of London Transport. Originally they were intended to replace London’s Trolleybuses (which finished in 1962) and older buses although eventually they replaced all previous designs.

The first production Routemasters appeared in 1959 and production continued until 1968. A total of 2,876 were built in a variety of versions: the standard, short RM with open rear platform, the lengthened RML (prototype in 1961, production 1965-68), the Green Line and London Country RMC coach (1962) with rear doors, the lengthened RCL Green Line coach (1965), the front entrance with doors RMF (1962) for Northern General, the front entrance with doors RMA (1964) for British European Airways, and the re-designed, experimental prototype, rear-engined, front entrance with doors FRM (1966), which never entered production. Two types of AEC and one type of Leyland engine were installed and the design proved amenable to several different engines being retrofitted.

The Routemaster was built jointly by AEC (chassis and mechanics) and Park Royal (body work and assembly). Although of a conventional layout, the design was highly innovative (borrowing much from the aircraft industry) with integral construction, aluminium bodywork, independent front suspension, power steering, fully automatic gearbox and power-hydraulic brakes.