Jowett Cars Ltd was formed and the first Jowett Seven introduced in 1920. The Seven was improved from 1923 until in 1936 the ubiquitous 7hp flat twin engine was enlarged to 946cc engine and took the cars into the 8hp taxation class. But at the same time the Jowett brothers were experimenting with a new four cylinder, although the first upright inline four was not satisfactory. However, for 1936 a new 1,166cc flat four engine was introduced in new 10hp saloons, the Jupiter and the Jason. Their over streamlined bodies were not to everybody's taste and later in the year a new 10hp model was created on the old flat twin chassis and with more restrained bodywork. Production continued until the war intervened and 1,582 cars were produced 1937-40. The Ten did not restart after WWII because new manager Calcott Riley had already commissioned the car which under designer Gerald Palmer would be launched as the all new Jowett Javelin.