Hawker Siddeley P.1127 GR.1" designation. The Harrier went on to become a successful aircraft in British service, and was exported to several nations, often seeing usage as a carrier-based aircraft. The P.1127/Kestrel was an experimental V/STOL aircraft, which served as the forerunner for the production of the Hawker Siddeley Harrier and the wider Harrier Jump Jet family. It served to demonstrate an entirely original technique of flight, as well as to trial a brand new type of engine in the form of the Pegasus turbofan engine. Despite this, the aircraft employed a principally conventional structure which, according to Mason, lent itself favourably to
British Aerospace Harrier II experience had highlighted demand for a more capable aircraft. The British government had only a minor requirement, for up to 60 Harriers at most and competing pressures on the defence budget left little room for frivolous expenditure such as the Advanced Harrier. A lack of government backing for developing the necessary engine of the new aircraft, the "Pegasus 15", led Hawker to withdraw from this project in 1975. Due to US interest, work proceeded on the development of a less ambitious successor, a Harrier fitted with a larger wing and making use of composite materials in its construction. Two prototypes