The Bedford S was produced in Great Britain between 1950 and 1959. Known as the "Big Bedford", it was the largest Bedford lorry available at the time, with a gross vehicle weight of 7 tons. At introduction, the lorry was fitted with a 4.92 L 6-cylinder Bedford petrol engine that produced 110 bhp (82 kW) at 3200 rpm. Drive was through a four-speed manual gearbox featuring synchromesh on the top three gears, and final drive in the rear axle was by hypoid gears. The Perkins R6 diesel engine was made an option in 1953, soon joined by the Leyland O.350, and Bedford's own diesel in 1957.

The Bedford S was used extensively by haulers and general trades through the 1950s and 1960s. The chassis was also used for fire engines, most enduringly, the Green Goddess military fire appliance.