After the cancellation of the TSR-2, the RAF eventually filled the tactical strike requirement using McDonnell F-4 Phantom IIs with US dual-key nuclear weapons, but continued their attempts to get the 10 kt limit lifted. Development of WE.177A was delayed by several years due to the Atomic Weapons Research Establishment (AWRE) at Aldermaston being inundated with work on other warhead developments. AWRE workload eased after completion of the Polaris missile warheads and work was able to resume on the WE.177A, deliveries to the RAF beginning in late 1971 for deployment on Buccaneers of RAF Germany, a year after WE.177A deliveries to the Royal Navy. Approval for high-yield tactical weapons was eventually gained in 1970 and, by 1975, the RAF had WE.177C, which at almost 200 kt was a weapon very similar to what they had planned for the TSR-2 in 1959. EE had put forward a delta winged design and Vickers, a swept wing on a long fuselage. The EE wing, born of their greater supersonic experience, was judged superior to Vickers, while the Vickers fuselage was preferred. In effect, the aircraft would be built 50/50: Vickers the front half, EE the rear.