The prototype M.5 Sparrowhawk was developed from standard Miles Hawk components as an entry into the King's Cup Race of 1935 piloted by F.G.

The top decking was reduced in height, a special high-compression version of the de Havilland Gipsy Six engine was fitted, and the undercarriage track was widened.

In 1936 Victor Smith entered Sparrowhawk G-AELT into the Schlesinger Race from Portsmouth to Johannesburg but had problems with oil after Salonika and eventually retired in Khartoum.

The sixth Sparrowhawk was modified with short span wings and wide chord flaps for experimental work.

The Sparrowjet was powered by two Turbomeca Palas gas turbine engines fitted in the wing roots and eventually achieved its original purpose and Dunkerley won the King's Cup Race in 1957 at an average speed of 228 mph (367 km/h).