The sponsors required a British brand name for the engine and Napier was chosen. Dunlop's tyres were not warranted safe beyond so the planned maximum of was pulled back. To minimise frontal area Irving based the shape of the nose on the racing Supermarine S.5's cowling. Leading fairings in front of the front wheels gave no useful improvement and they were abandoned. An irreducible minimum was arrived at for the size of the cockpit because it had to be large enough for a sixteen-inch steering wheel believed to be needed to give sufficient leverage. In the end a large tail fin was adopted in case of side gusts, it located the centre of gravity an inch in front of the centre of pressure. The whole shell was shaped to exert a downward air pressure to keep the driving wheels on the ground and assist stability but a further of lead ballast was added to the tail. The twin prop-shafts were given strong casings in case they came apart at high speed. The axle was given no differential. At that time the car was notable among land speed record cars for having 4-wheel brakes. Suspension was by half-elliptic leaf springs all round, axle travel was limited to just 1¼ inches in front and 1¾ at the rear axle. The car was built at KLG Works on Kingston Hill.