Additional prototypes were used for the development of improved variants of the Hornet. "PX312", participated in the development of an improved fighter model to succeed the F.1, the Hornet F.3. "PX212", "PX214", and "PX219", were converted by the Heston Aircraft Company from Hornet F.1 standard aircraft to represent and test aspects of the initial naval version, later named "Sea Hornet F.20". "PX212" and "PX214" were only partially naval, being outfitted with arrestor hooks but lacking the wing-folding mechanisms of subsequent production aircraft; "PX219" was the full naval version and later conducted carrier deck trials on board the aircraft carrier .