The Cierva Autogiro Company was a British firm established in 1926 to develop the autogyro. The company was set up to further the designs of Juan de la Cierva, a Spanish engineer and pilot, with the financial backing of James George Weir, a Scottish industrialist and aviator.
Cierva's first British-built autogyro was the C.8 design. It and some other designs were built in conjunction with Avro. The pre-war Cierva C.30 proved popular. Nearly 150 were built under licence in the UK (Avro), Germany (Focke-Wulf) and France (Lioré-et-Olivier).
^Marsh had been with Cierva since 1932 and had been its instructor at the autogyro flying school. During the war he had flown autogyros for radar development
^Cable had learnt to fly under Marsh and had been a Cierva employee before the war. During the war, he had been Commanding Officer of the "Research, Development and Training Unit for Rotary Wing Aircraft"