Air Defence Experimental Establishment

In 1924 the Searchlight Experimental Establishment was renamed the Air Defence Experimental Establishment. Its interests were extended to cover acoustical devices and gun sound ranging and, from 1936, radar. It was situated at Biggin Hill until it moved to Christchurch in 1939. In the same year the Ministry of Supply took over responsibility for it from the War Office. It was renamed the Air Defence Research and Development Establishment in 1941.