The British government feared resurgence of United States isolationism , as had occurred after the First World War , in which case the UK might have to fight an aggressor alone ; or that the UK might lose its great power status and its influence in world affairs . It therefore restarted its own development effort , now codenamed High Explosive Research . The first British atomic bomb was tested in Operation Hurricane on 3 October 1952
Operation Hurricane
Operation Hurricane
Polaris (UK nuclear programme)