The T.K.4 was built by students at Stag Lane Aerodrome in 1937 with the aim of building the smallest possible aircraft around the 140 hp (104 kW) de Havilland Gipsy Major II. It was a low-wing monoplane with a conventional retractable landing gear and had a variable-pitch propeller and was fitted with slots and flaps. The only T.K.4, registered G-AETK, was first flown on 30 July 1937. It was 9th in the 1937 Kings Cup Race at a speed of 230.5 mph. The aircraft crashed on 1 October 1937 killing the pilot R.J. Waight while he was attempting a 100 km class record.