Marshall rebuild RM class Routemasters

English: In the early 2000s, in an attempt to increase the number of Routemaster buses in service in the centre of the capital, Transport for London purchased 48 second hand examples of the RM class for rebuilding and re-entry into London service.

The rebuilding work involved a mechanical overhaul, including the replacement of the major drivetrain elements - the engine, gearbox and retarder (Cummins B-Series, Allison & Voith respectively), and a complete re-wiring of the electrics. It also included a comprehensive refurbishment, inside and out. Due to this work, the rebuilds don't sound the same as 'classic' RMs. There are also minor visual differences - the rear light clusters and the opening windows (changed from winders to hoppers) - and at night, the interior fluorescent lighting strips look different to the previous bulb based system. The buses are referred to as the Marshall rebuilds because the work was carried out by Marshall Bus at their premises in Cambridge, although because that company ceased trading in 2002, some of the later buses were passed through the Cummins (Wellingborough) plant and then refurbished by Arriva London.

The buses came from a variety of sources, including preservation and private non-PSV uses. The largest single source were ex-Reading Mainline examples. The first batch were used to completely replace the buses on route 13, later batches were used to supplement other routes, notably the 19, 36 & 38. Their use in London was short lived - conversions of Routemaster routes having begun in 2003, even as the rebuilds continued. Allocations of some of the rebuilds changed as the pool of routes got smaller, with several finding their way onto the last standard Routemaster route, the 159, which was converted in December 2005. Being relatively new, 20 of the rebuilds were selected for further use in London service beyond 2005, as the Heritage Routemasters (entering service in November 2005).

The rebuilt buses were (* - denotes the Heritage Routemasters):