The XK120 was a late decision to provide a ‘concept’ to show off Jaguar’s new XK twin camshaft 3.4 litre 6-cylinder engine. Fitted to a shortened version of a new chassis destined for a luxury saloon and clad with an all aluminium two-seater roadster body style, the car was such a success when launched at the British Motor Show in 1948 that Jaguar had to move the car over to full scale production. As the name implies the car was capable of up to 120mph (proved on numerous occasions by public exhibition).

By 1950 bodywork production had moved over to all steel and in 1951 an additional model, the Fixed head coupe was produced, at the time unique in having saloon car interior appointments including wind up side widows, lockable doors and wood veneered dashboard. In 1953 a further new model was added, the Drop head coupe providing the benefits of open top motoring, but with a quick action hood and luxury appointments. The XK120 stayed in production until 1954 when the XK140 was introduced.