New to London Transport in December 1961, RML 901 was one of the first batch (a total of 24 vehicles) of 30 foot Routemasters coded RML, (with the L standing for Long or Lengthened). The bus started its working life at Finchley garage on route 104 (North Finchley and Moorgate) which had replaced trolleybus route 609 in November 1961. In June 1966 the bus moved to New Cross as a training vehicle but returned to Finchley in February 1968 after its first overhaul. It operated on route 38 until October 2005.
In January 1971 RML 901 moved the short distance to Muswell Hill to work on route 43 between Friern Barnet and London Bridge. In December 1974 DM type vehicles started to appear on route 43 so RML 901 moved to Holloway (HT) to work on route 14 (Hornsey Rise and Putney). In February 1975 the vehicle received its second overhaul and moved south of the river to Stockwell to work on routes 37 and 88.
After 5 years at Stockwell a third overhaul was due and a move to Hackney followed but only for three months before a move to Cricklewood for the conversion back to Routemaster for route 16.
A 4th Overhaul in March 1983 took the bus to Ash Grove (the new garage that replaced Hackney and Dalston). It was here in 1990 that its AEC engine was replaced with a Cummins C series. With the closure of Ash Grove RML 901 moved up the road to Clapton to work on route 38 where it was to stay for the next 14 years. In June 1992 it was refurbished at South Yorkshire Transport, Rotherham.
RML 901 is remarkable in the Routemaster family, as it has retained its original body throughout the last 45 years, a feature that really secured its place in the heritage fleet.