A very small team of draughtsmen designed one of the cleanest and most efficient aeroplanes of the whole Miles series in just under a year during 1937, which was an outstanding achievement for the leisurely days of peace.
The machine was the Kestrel Trainer - forerunner of the famous Master range - and its production was a private venture by the Company, primarily to supply an instructional aircraft whose performance and characteristics approximated to those of the Hurricane and Spitfire single-seat fighters, then in limited production for the RAF.
Fitted with the Rolls Royce Kestrel XVI engine, the Kestrel Trainer was Mr. Miles' first venture into the realms of high-powered aircraft and its initial test flight, which he made on an early summer evening in 1937, demonstrated to those present that the machine would make history. The performance exceeded the designer's most optimistic hopes, the top speed of 296 mph at 14,000 feet being only 15 mph below that of the contemporary Hurricane - and an all-time record for standard two-seat aircraft of similar power.
Although the Kestrel was admitted to be the fastest two-seat trainer of its time, and had attracted favourable attention at the 1937 R.A.F. Display, its acceptance for Service use was regarded in official circles as being "premature" - a word painfully associated with the immediate pre-1939 period - but the march of events reversed this attitude at the eleventh hour, and the Kestrel eventually went into production as the Master I, the contract being the largest ever placed for a training aeroplane.