Hawker Siddeley Harrier cancelled after the release of the British Government's 1957 Defence White Paper, which advocated a policy shift away from manned aircraft and towards missiles. This policy resulted in the termination of the majority of aircraft development projects then underway for the British military. Hawker sought to quickly move on to a new project and became interested in Vertical Take Off/Landing (VTOL) aircraft, which did not need runways. According to Air Chief Marshal Sir Patrick Hine this interest may have been stimulated by the presence of Air Staff Requirement 345, which sought a V/STOL ground attack fighter for the Royal Air
Hawker Siddeley P.1127 after the P.1154's selection over the Dassault Mirage IIIV. Following the termination of the P.1154, the RAF then began studying a straightforward upgrade of the Kestrel as a production aircraft; accordingly, it issued Requirement ASR 384, which sought a V/STOL ground attack jet, known as the "P.1127 (RAF)". In late 1965, the RAF placed an order for six pre-production P.1127 (RAF) aircraft. On 31 August 1966, the first of these P.1127 (RAF) aircraft made its maiden flight. In early 1967, an order for 60 production aircraft was formally received by Hawker Aviation; at this time the aircraft received the "Harrier