During the early part of the Second World War , Britain had a nuclear weapons project , code-named Tube Alloys , which the 1943 Quebec Agreement merged with the American Manhattan Project to create a combined American , British , and Canadian project . The British government expected that the United States would continue to share nuclear technology , which it regarded as a joint discovery , but the United States Atomic Energy Act of 1946 ( McMahon Act ) ended technical co-operation . Fearing a resurgence of United States isolationism , and Britain losing its great power status , the British government restarted its own development effort , which was given the cover name " High Explosive Research " . The first British atomic bomb was tested in Operation Hurricane at the Montebello Islands in Western Australia on 3 October 1952
Operation Hurricane
Operation Hurricane
Operation Totem