The AEC RML Routemaster Bus
RML3 is one of four prototype Routemasters built and tested between 1954-1958 before full-scale production began. It was taken into stock in July 1957 and entered service in January 1958, allocated to Willesden garage for use on route 8 into and across central London.
One of the two prototypes to have a Leyland engine, it became the only Routemaster to have a body built by Weymann of Weybridge/Addlestone in Surrey at their now long-gone factory just up the road from today’s Museum.
In January 1959 it was involved in a severe collision in the Edgware Road and suffered extensive frontal panel damage. After repair in London Transport’s experimental workshop at Chiswick Works, it was returned to service until November 1959 when its service career ended after only 18 months. It then became a driver-training vehicle in preparation for the introduction of production Routemasters to replace London’s electric trolleybus fleet. In 1961, the bus was re-classified as ‘RM3′ to allow the ‘RML’ designation to be used for the new longer Routemasters.
This information is from the London Bus Museum, and more information can be found here