Launched in autumn 1928, The Armstrong Siddeley Twelve continued their all six cylinder model line up, with the Twelve being given a 1236cc sidevalve engine that was not really up to the task of propelling the heavy bodies it was fitted with. However the engine was enlarged to 1434cc in 1931 and production continued until 1937, selling 12,500 along the way. A new 'Twelve Plus' model was launched in 1936 with an improved engine of 1666cc and a new longer chassis. A new type of clutch was fitted as an improvement and the car became known as the 'Armstrong Siddeley Fourteen' and stayed in production until 1939.