The test establishment received the first flying test bed aircraft during the early part of 1935, a Gloster Gnatsnapper, a Hawker Fury and a Hawker Hart. Testing of the Rolls-Royce Kestrel took place to optimise performance and maintain superior reliability. In 1936 Rolls Royce purchased a German Heinkel He70 airliner registration G-ADZF delivered to Hucknall fitted with a Rolls Royce supplied Kestrel engine. Then the fastest aircraft available "öff the shelf". In 1938 Rolls Royce fitted a Rolls Royce Peregrine engine which raised the aircraft's top speed to 300 mph. (Ref Flight International 29 April 1971 "The evolution of Hucknall")