Seven hundred RF class single-deck buses were built for London Transport between 1951 and 1954. The first 25, designed for tour and private hire work, were 27′ 6″ long, but the remainder were built to the newly permitted length of 30′. 263 were built for Green Line Coach services, whilst the remainder were for bus work – 225 for the Central Area and 185 for the Country Area. The vehicles were based on the AEC Regal MkIV chassis, built at Southall, and bodied by Metropolitan Cammell in Birmingham. The AEC 6-cylinder 9.6 litre engine was mounted horizontally below the floor, transmission being through a four speed air operated pre-selective gearbox and fluid flywheel.