After the war, London Transport’s fleet needed major renewal.  First to be dealt with were the double-deckers, involving the production of nearly 7,000 of the RT family.  Once these were nearing completion, LT turned its attention to the single-deck fleet.  Using ideas from the pre-war Q and underfloor-engined TF classes, the RF used a similar 9.6 litre AEC diesel engine to the RT, but laid on its side under the floor.  The first of 700 was delivered in 1951.

 

Following the introduction of RFs on Green Line services, the 225 red RFs were delivered in 1952 and 1953.  Initially, the red buses had no doors (or heaters), the absence of doors being a requirement of the Metropolitan Police as it was supposed they would slow down boarding and delay the traffic.  Doors were fitted progressively to the fleet as buses were converted for one-man operation, with the last doorless buses, the last running with conductors, on route 236 in 1971.

 

At 30 feet, the red buses were built to the then maximum permitted length and originally carried 41 passengers, this being reduced to 39 by the addition of a luggage rack when converted for one-man operation.  Other changes over the years included the fitting of indicator 'ears' in 1956 and the fitting of heaters.

 

The conversions enabled the introduction of large-bus OMO in the Central Area - on four routes in 1964, 15 years after the last OMO 20-seat Cubs ran on the 238 and 252.  While the Merlins and Swifts came and went, RFs continued to run reliably through the 1970s, until finally replaced by BL-class Bristol LHs and Leyland Nationals.  The last few finished on Kingston's jointly-worked routes 218 and 219 on 30 March 1979.