London Transport placed four prototype Routemasters in service between 1956 and 1958.
The first two were built at the London Transport works at Chiswick, the third by Weymann at Addlestone and the fourth, an experimental Green Line coach, at Eastern Coach Works at Lowestoft.
The third and fourth had Leyland engines and mechanical units.
The Routemaster was first exhibited at the Earl's Court Commercial Motor Show in 1954.

In 1961, 24 longer RMLs (30 ft [9.14 m] compared with the standard 27 ft 6 in [8.38 m]) were built as a test, going into production from 1965.
In 1962, the front entrance RMF concept was tried, with RMF1254 based on the trial RMLs.
This was exhibited and toured, leading to the production of a small number of RMF and RMA buses.

In 1964, just before commencement of mainstream production of the RML, the final front-engined Routemasters, AEC started work on a front-entrance, rear-engined prototype, FRM1.
Completed in 1966, it saw regular London service, then on London Coaches tour operations, before being withdrawn in 1983.
It was nicknamed the Fruitmaster.
London Transport placed four prototype Routemasters in service between 1956 and 1958. The first two were built at the London Transport works at Chiswick, the third by Weymann at Addlestone and the fourth, an experimental Green Line coach, at Eastern Coach Works at Lowestoft. The third and fourth had Leyland engines and mechanical units. The Routemaster was first exhibited at the Earl's Court Commercial Motor Show in 1954.
In 1961, 24 longer RMLs (30 ft [9.14 m] compared with the standard 27 ft 6 in [8.38 m]) were built as a test, going into production from 1965. In 1962, the front entrance RMF concept was tried, with RMF1254 based on the trial RMLs. This was exhibited and toured, leading to the production of a small number of RMF and RMA buses.
In 1964, just before commencement of mainstream production of the RML, the final front-engined Routemasters, AEC started work on a front-entrance, rear-engined prototype, FRM1. Completed in 1966, it saw regular London service, then on London Coaches tour operations, before being withdrawn in 1983. It was nicknamed the Fruitmaster.
AEC Routemaster