Vickers had emerged from the Second World War as one of the world's pre-eminent companies in the field of aeronautical manufacturing and development. Furthermore, the company operated its own secretive Skunk Works-like development organisation based at Weybridge, Surrey, which had been involved in several secret wartime development projects. It was this secretive division in which the early stages of the development of the Valiant took place, including the later assembly of the initial two prototypes. Vickers initially produced a six-engine jet bomber design proposal to meet Specification B.35/46; as rapid progress in the development of more powerful jet engines had been made, this was re-worked to a four-engine proposal in 1948. The proposed design submitted by Vickers was relatively straightforward, being less aerodynamically advanced in comparison to competing bids made by rival firms.