In an attempt to gain the world speed record two Mk I airframes on the production line were strengthened, one of these (K9834) was then fitted with a special “sprint” version of the Merlin engine, shorter span wings and a long streamlined cockpit canopy. The Heinkel 100 and Messerschmitt 209 put the record out of reach of the Speed Spitfire and it was fitted with a standard Merlin XII engine and used as a high speed reconnaissance aircraft. It survived until 1946