Even before the Quebec Agreement was signed, Akers had already cabled London with instructions that Chadwick, Peierls, Oliphant and Simon should leave immediately for North America. They arrived on 19 August, the day it was signed, expecting to be able to talk to American scientists, but were unable to do so. Two weeks passed before American officials learned of the contents of the Quebec Agreement. Bush told Akers that his action was premature, and that the Combined Policy Committee would first have to agree on the rules governing the employment of British scientists. With nothing to do, the scientists returned to the UK. Groves briefed the OSRD S-1 Executive Committee, which had replaced the S-1 Committee on 19 June 1942, at a special meeting on 10 September 1943. The text of the Quebec Agreement was vague in places, with loopholes that Groves could exploit to enforce compartmentalisation. Negotiations on the terms of technical interchange dragged on until December 1943. The new procedures went into effect on 14 December with the approval of the Military Policy Committee (which governed the Manhattan Project) and the Combined Policy Committee. By this time British scientists had already commenced working in the United States.