Embodying considerable redesign by comparison with the Siskin II, the Siskin III featured an enlarged upper wing, a lower wing of reduced chord and Vee-type instead of parallel interplane struts. The Siskin III was powered by the 350hp Armstrong Siddeley Jaguar III engine, and was ordered for the RAF to Specification 15/22. The prototype was tested in 1923, the first production example flying on 24 March 1924. Armament comprised two 7.7mm Vickers machine guns, and 50 single-seat examples were built for the RAF, one of these later being passed to the RCAF. Twelve two-seat trainer models were also built.