This article concludes that Australia was determined to possess nuclear weapons from the end of the Second World War. The best prospects for this lay in working with Britain through the so-called ‘joint project’. British defence planners knew that their small island would not survive a future atomic blitz and, therefore, needed ‘active’ deterrent weapons. The problem was that the US after 1946 moved to protect its atomic monopoly and denied Britain research, raw materials, and test facilities. Australia was, therefore, an invaluable partner in the British deterrent weapons programme, in all its aspects from research to testing, as long as the US refused co-operation. The quest for atomic weapons lies at the heart of many of Canberra's initiatives after 1945 – the decision to build an Australian National University; the construction of the vast Snowy Mountains scheme; and ultimately the decision to deploy Australian forces into South-East Asia in the mid-fifties. The height of Anglo-Australian co-operation coincided with the atomic tests after 1952, London's decision to help build atomic reactors in Australia, and the Suez crisis. Britain's acquisition of deterrent weapons in 1957, however, saw the end of imperial co-operation on atomic weapons and delivery systems.