The Armstrong Siddeley Cheetah IX was one in a long line of successful engines whose basic design had remained unchanged since 1919.

The Cheetah IX was used to power the Avro Anson Mk. I, an operational RAF bomber at the beginning of the war and one of the first twin-engined aircraft to be utilized by the British Commonwealth Air Training Plan. Anson Mk. I's were brought to Canada early in the war to begin the training of aircrew under the BCATP.

Cheetah engines also powered the British built Airspeed Oxford twin-engined trainer. A total of 35,000 Cheetahs had been produced by the end of WW II.