and accepted as practical. The aircraft would have been armed with the Red Top missile. In November 1962, Rolls-Royce offered a PCB-equipped vectored thrust twin-Spey design as an alternative to the BS100. This alternative engine arrangement was widely seen as inferior, particularly due to the danger posed by asymmetric thrust output if a single engine failure occurred; however, Rolls-Royce claimed that their solution could be available sooner than the BS100 would be. In December 1962, Bristol performed the first successful run of a PCB-equipped Pegasus 2 engine. In order to perform a vertical takeoff, the use of PCB was necessitated; however, this feature would have come at the cost of significant ground erosion during operations. In December 1962, HSA dedicated its full effort to developing the RAF's single seat variant; Wood notes the starting point for which was broadly similar to the proposal submissions for NBMR-3. On 18 February 1963, Julian Amery, the Minister of Aviation, confirmed that the project study contract had been placed; on 25 March, Amery announced that the BS100 had been selected as the powerplant to be used on the P.1154. At this point, the program was envisioned to involve the ordering of a total of 600 aircraft, 400 for the RAF and 200 for the Royal Navy. However, as HSA carried out further work on the detailed design phase of the programme, it was becoming clear that opinions on the internal equipment for the aircraft varied substantially between the two services. The difficulty of handling the divergent requirements was compounded when, in May 1963, shortly following on from the official issuing of Specification OR356/AW406, the option of having two distinct aircraft was rejected; the Secretary of State for Defence, Peter Thorneycroft, had insisted upon the development of a single common aircraft to meet the requirements of both services. According to Wood, Thorneycroft's decision had been influenced by the American General Dynamics F-111 multirole program, and had sought to duplicate this development concept for the P.1154. Despite a stated Navy preference for a swing-wing fighter, the services agreed that the aircraft would be completely common, with the exception of different radar systems. However, upon requests by various electronics manufacturers to the Ministry of Aviation to be issued with the requirements for the electronics fit, no response was ever issued; this lack of leadership proved disruptive to the overall programme. Disfavour and cancellation As a consequence of