In the first week of July, 1935, F. G. Miles decided to race for the King's Cup in the following September, even though at that point there was no machine available for him, and with only eight weeks until the race, there was little time to produce a suitable aircraft!. However, in those few weeks Mrs. Miles devised and directed the construction of a racing aircraft which was both fast, manœuvrable, and pleasing to the eye.

First, a standard Hawk fuselage was taken from the production line and shortened by two feet, then standard Hawk outer wings were fitted direct to the fuselage, without the usual centre-section. Long range fuel tanks and a low, single-strut type undercarriage were next fitted, together with a standard Hawk tail, the job being rounded off with a 140 hp high compression Gipsy Major engine. With a highly polished cream and red finish, the machine was ready on time and was named the Sparrowhawk.

The 1935 Race was flown over two courses, the first, on one day, being a circuit of Britain, while the second day's flying was over seven laps of a triangular course of 50 miles, both events starting and finishing at Hatfield. The first day's racing resolved itself into a thrilling duel between the only designer-pilots in the competition - F. G. Miles and Edgar Percival.

Fifth man to leave Hatfield, Mr. Miles dead-heated for second place at the Glasgow control and had achieved that position outright by the time he reached Belfast, which was the only point at which he had to refuel, thanks to the long-range tanks. At the last control, Cardiff, Mr. Miles touched down as the leader, Mr. Percival, took off on the last stage to Hatfield, but, stopping there only three minutes, he continued the pursuit and caught his rival literally "on the post", thus winning the speed prize, at an average of 163.84 mph for the 953 miles circuit.

In the following day's speed race the Sparrowhawk finished eleventh, at 172.38 mph, but the pilot was quite happy, as his designs had taken the first three places in the Race!

Several Sparrowhawks were built, including two for special high-lift flap research.