be used for making concrete. The work afloat and ashore was complemented by Royal Australian Air Force (RAAF) aerial photography of the islands. The British survey team returned to London on 29 November 1950. The islands were assessed as suitable for atomic testing, but, for climatic reasons, only in October. On 27 March 1951, Attlee sent Menzies a personal message saying that, while negotiations with the United States for use of the Nevada Test Site were ongoing, work would need to begin if the Montebello Islands were to be used in October 1952. Menzies replied that he could not authorise the test until after the Australian federal election, to be held on 28 April 1951, but was willing to allow work to continue. Menzies was re-elected, and the Australian government formally agreed in May 1951. On 28 May, Attlee sent a comprehensive list of assistance that it hoped that Australia would provide. A more detailed survey was requested, which was carried out by in July and August 1951. The British government emphasised the importance of security, so as not to imperil its negotiations with the United States. The Australian government gave all weapon design data a classification of "Top Secret", other aspects of the test being "Classified". Nuclear weapons design was already covered by a D notice in the United Kingdom. Australian D Notice No. 8 was issued to cover nuclear tests. Meanwhile, negotiations continued with the Americans. Oliver Franks, the British Ambassador to the United States, lodged a formal request on 2 August 1951 for use of the Nevada Test Site. This was looked upon favourably by the United States Secretary of State, Dean Acheson, and the chairman of the United States Atomic Energy Commission, Gordon Dean, but opposed by Robert A. Lovett, the American Deputy Secretary of Defense and Robert LeBaron, the Deputy Secretary of Defence for Atomic Energy Affairs. The British government had announced on 7 June 1951 that Donald Maclean, who had served as a British member of the Combined Policy Committee from January 1947 to August 1948, had been a Soviet spy. In view of security concerns, Lovett and LeBaron wanted the tests to be conducted by Americans, British participation being limited to Penney and a few selected British scientists. Truman endorsed this counterproposal on 24 September 1951. The Nevada Test Site would be cheaper than Montebello, although the cost would be paid in scarce