Early post-war steel shortages meant that the body was built from aluminium, using rubber press tools that had been used making panels for the largely wooden bodied Mosquito bomber that had been built by Standard during the war. The frame was hand welded up from steel tube. The engine was a version of Standard's 1.5-litre, four-cylinder side-valve design that had been converted to overhead valves by Harry Weslake and built by Standard exclusively for SS-Jaguar before World War II. The Triumph version featured a downdraught Solex carburettor instead of the Jaguar's side-draught SU, and a 6.7:1 compression ratio instead of 7.6:1. A four-speed gearbox with synchromesh on the top three ratios was used.