cover in the form of an Intention to Proceed (ITP) order to Avro in November 1947. An advisory committee selected the Handley Page design on 23 December 1947, and it too was given an ITP. The 17 December 1946 meeting that came up with OR230 also decided to solicit bids for a more conservative design that could be put into service more quickly, and could act as further insurance against the failure of both of the more advanced designs. This was expressed in another operational requirement (OR239), from which an Air Ministry specification, B.14/46, was generated, which was issued on 11 August 1947. This had lower cruising altitude and speed requirements than B.35/46, but was otherwise identical. A design was put forward by Shorts, which was given an ITP in November 1947. The result was an extremely conservative design with straight wings, the Short Sperrin, which was in practice little more than a jet-powered Lincoln. Meanwhile, Vickers-Armstrong had produced a swept wing design, the Vickers 660. This had been rejected because it did not meet the B.35/46 specification; but the estimated performance of the Sperrin caused officials at the Air Ministry to take another look. A new specification, B.9/48, was drawn up, based on the Vickers-Armstrong design, which was issued on 19 July 1948. An ITP was given to Vickers-Armstrong in April 1948, followed by a contract for two prototypes in February 1949, whereas Shorts was only awarded a contract for two prototypes in February 1949. The first prototype Vickers 660 flew on 18 May 1951, three months before the first prototype Sperrin, which first flew on 10 August 1951. No longer required, the Sperrin was cancelled; only the two prototypes were built. Vickers-Armstrong named its aircraft the Vickers Valiant. Hitherto, bombers had been named after British or Commonwealth cities, but in October 1952 the Air Ministry decided to adopt alliterate names, with the other designs becoming the Avro Vulcan and the Handley-Page Victor. Henceforth, the three would be known as the V bombers. While more expensive than the approach of building one bomber design per category, the RAF insisted on having choice. Air Chief Marshal Sir John Slessor believed that had the air force been forced to choose among the three British bombers under development in the late 1930s—the Avro Manchester, Short Stirling, and Handley Page Halifax—it would have chosen the wrong one. As a stop gap, the British