Built 1960. This is the first prototype P1127 and the first to achieve a vertical take-off, on 21st October 1960. The P 1127 developed into the Kestrel and then the Harrier, the world's first operational vertical take-off and landing (VTOL) jet fighter. The second generation of Harrier remains in service with various international air arms, including the US Marines. Initially on display at the RAF Museum at Hendon, XP831 is now on display in the ‘Flight’ Hall of the Science Museum, South Kensington, London.