The bus was developed during the period 1947-1956 by a team led by Douglas Scott, the brief being to replace the trolleybuses, which had themselves replaced trams. The buses were originally constructed at the AEC works in Southall. The original concept included the maintenance of the Routemaster at Aldenham Garage. Here the buses could be completely stripped down and rebuilt, engines changed etc. which was an important part of the original concept. However, as the number of Routemasters in London got smaller this concept was abandoned, and Aldenham garage closed sometime in the early 1970s.Production examples, at first to the 27 feet 6 inches (8.4 metres) length then permitted, were placed in service from 1959 to replace trolleybuses, this was completed in May 1962. Subsequent Routemasters, the last 500 of which were 30 feet (9.1 metres) long RML types, began replacing the previous generation of RT-type AEC Regent buses and their similar Leyland Titan RTL and RTW counterparts. These are often mistaken for Routemasters by the public and by the media. The last Routemaster, RML 2760, entered service in March 1968.