British military researchers at the Telecommunications Research Establishment (TRE) Samuel C. Curran, William A. S. Butement, Edward S. Shire, and Amherst F. H. Thomson conceived of the idea of a proximity fuze in the early stages of World War II. Their system involved a small, short range, Doppler radar. British tests were then carried out with "unrotated projectiles," in this case rockets. However, British scientists were uncertain whether a fuze could be developed for anti-aircraft shells, which had to withstand much higher accelerations than rockets. The British shared a wide range of possible ideas for designing a fuze, including a photoelectric fuze and a radio fuze, with United States during the Tizard Mission in late 1940. To work in shells, a fuze needed to be miniaturized, survive the high acceleration of cannon launch, and be reliable.