The Armstrong Whitworth Siskin was a biplane fighter aircraft of the 1920s. The design was a development of the Siddeley Deasy S.R.2 Siskin (Siddeley Deasy was Armstrong Whitworth's parent company). The fighter was the first all-metal fighter in the Royal Air Force, the air force of the United Kingdom. The Siskin was used by eleven RAF squadrons as well as by a number of other nations including Canada, which used the type up to 1939. The Siskin IIIA was powered by the Armstrong Whitworth Jaguar IV engine, which gave a maximum speed of 156 mph (251 km/h).