areas of the Manhattan Project. In particular, it could benefit enough from assistance from Chadwick and one or two other British scientists to warrant the risk of revealing weapon design secrets. Bush, Conant and Groves wanted Chadwick and Peierls to discuss bomb design with Robert Oppenheimer, and the construction company Kellogg wanted British comments on the design of the gaseous diffusion plant it was building. Negotiations Churchill took up the matter with Roosevelt when they met at the Washington Conference on 25 May 1943. A meeting was arranged that afternoon between Cherwell and Bush in Hopkins's office in the White House, with Hopkins looking on. Both stated their respective positions, and Cherwell explained that Britain's post-war interest was in nuclear weapons, and not commercial opportunities. Hopkins reported back to Roosevelt, and Churchill and Roosevelt agreed that information interchange should be reviewed, and that the atomic bomb project should be a joint one. Hopkins sent Churchill a telegram confirming this on 17 June, but American policy did not change, largely because Roosevelt did not inform Bush when they next met on 24 June. When Churchill pressed for action in a telegram on 9 July, Hopkins counselled Roosevelt that "you made a firm commitment to Churchill in regard to this when he was here and there is nothing to do but go through with it." Bush was in London on 15 July 1943 to attend a meeting of the British War Cabinet's Anti-U-Boat Committee. Sir Stafford Cripps took him to see Churchill who told Bush that the President had given him his word of honour on full co-operation, and that he was incensed at obstruction by American bureaucrats. Bush suggested that he take up the matter with Stimson, who was also in London. Churchill did so on 17 July, and Stimson promised to submit the matter to Roosevelt. On 20 July, Roosevelt wrote to Bush with instructions to "renew, in an inclusive manner, the full exchange with the British Government regarding Tube Alloys", but since Bush was in London, he did not see this letter for another ten days. Stimson, Bush and Stimson's special assistant, Harvey Bundy, met Churchill, Cherwell and Anderson at 10 Downing Street in London on 22 July. None of them was aware that Roosevelt had already made his decision. Stimson had just finished a series of arguments with the British about the need for an invasion of France.