Ellis, Otto Reder, and Dr. J.A.J Bennett and was assembled by the British Aircraft Manufacturing Company at London Air Park, Hanworth.

[1][2] The C.40 was the last autogiro produced by the Cierva Autogiro Company, Ltd. Design commenced in July 1936 and continued after Cierva's death in an airliner crash in December of that year.

Based on the C.30A Autogiro the C.40 was originally intended to use a higher power version of the Armstrong Siddeley Genet Major engine.

It had two side-by-side seats in a wooden fuselage and the production version was powered by a Salmson 9NG radial engine, problems with which delayed introduction of the C.40 into service until mid-1938.

[2] The remaining two were registered to the Cierva Autogiro Company, one was lost in France in June 1940, and the other was impressed into RAF service.