During the early part of the Second World War , Britain had a nuclear weapons project , codenamed Tube Alloys , which the 1943 Quebec Agreement merged with the American Manhattan Project . The British government trusted that the United States would continue to share nuclear technology , which it regarded as a joint discovery , after the war , but the United States Atomic Energy Act of 1946 ( McMahon Act ) ended technical co-operation . The British government saw this as a resurgence of United States isolationism , as had occurred after the First World War , and dreaded the possibility that Britain might have to fight an aggressor alone . It also feared that Britain might lose its great power status and its influence in world affairs . It therefore restarted its own nuclear weapons development effort , which was now codenamed High Explosive Research . The first British atomic bomb was tested in Operation Hurricane on 3 October 1952
Operation Hurricane
Operation Hurricane
V bomber