Vickers V-1000 the world's first jet-powered commercial transport aircraft, the Vickers Viscount, the world's first turboprop-powered commercial airliner, and the Bristol Britannia, a turboprop-powered aircraft capable of conducting routine transatlantic flights; all of these designs had their origins in the specifications laid out by the wartime Brabazon Committee. With these aircraft, Britain appeared to be on track to capturing a large slice of the global demand for civil aircraft for the foreseeable future. Meanwhile, the Royal Air Force (RAF) had been pursuing development of a new generation of strategic bombers, these being the Vickers Valiant, the Avro Vulcan, and the Handley Page
Vickers Valiant deterrent to the Soviet Union from acts of aggression in Europe. In April 1948, the Air Staff issued a specification with the designation B.9/48 written around the Vickers design, which was given the company designation of Type 660; an 'Instruction to Proceed' was received by Vickers on 16 April 1948. In February 1949, two prototypes of the aircraft were ordered. The first of these was to be fitted with four Rolls-Royce RA.3 Avon turbojet engines, while the second was to be fitted with four Armstrong Siddeley Sapphire engines as the Type 667. On 18 May 1951, the first prototype, serial