The Avro 631 Cadet was developed in 1931 as a smaller, more economical, derivative of the Tutor military trainer, for flying club or personal use.

In turn, this formed the basis for the more powerful Avro 643 Mk II Cadet; it was also strengthened and had improved parachute egress.

This model entered service in 1935, and was built in the largest numbers, including 34 fitted with a tailwheel for the Royal Australian Air Force.

[1] The Cadet, while smaller and more economical than the Tutor, was still more expensive to run than competing two-seat light civil aircraft and was harder to hangar because of its lack of folding wings, so it was used mainly as a trainer for flying schools or the military.

[1] The other major operator was the RAAF, which acquired 34 Mk II Cadets, delivered between November 1935 and February 1939.