The Boat Churchill, the Royal Navy's fourth nuclear-powered fleet submarine was ordered on 21 October 1965, and was laid down at Vickers Shipbuilding and Engineering Limited (VSEL)'s Barrow-in-Furness shipyard on 30 June 1967. The submarine was launched by Mary Soames, Winston Churchill's youngest daughter, on 20 December 1968 and commissioned on 15 July 1971. Churchill was chosen to trial the first full-size submarine pump jet propulsion. Trials of a high-speed unit were followed by further trials with a low-speed unit, and these were successful enough for the same propulsion to be fitted in the rest of the class. Photosof these trials are still classified Later British submarine classes also featured the pump jet, although first-of- class vessels Swiftsure and Trafalgar were fitted with propellers at build. Displacement: 4,900 tonnes Length: 86.9 m (285 ft 1 in) Beam: 10.1 m (33 ft 2 in) Draught: 8.2 m (26 ft 11 in) Propulsion: 1 Rolls-Royce PWR nuclear reactor, 1 shaft Speed: 28 knots (32 mph; 52 km/h) submerged Depth Those on board knew what she was good for ! Complement: 103 Armament: 6 × 533 mm (21 in) torpedo tubes Mark 8 torpedoes Tigerfish torpedoes RN Sub Harpoon missiles