A negotiating team from the British Admiralty came to the United States to negotiate a detailed agreement between the United States and Great Britain. The polaris sales contract was signed on April 6, 1963. After the approval of this agreement, work began in earner and has continued at a steady pace since then. VADM R. N. MacKenzie was appointed Chief Executive POLARIS (CPE) and was authorized to use MOD (N) personnel for the production of submarines, ground support and mechanical and electrical equipment. The Ministry of Buildings and Public Works has the primary responsibility for providing onshore facilities to support and maintain the entire system. The Department of Aviation is responsible within the United Kingdom for the acquisition of the POLARIS rocket, including the re-entry system and any necessary support equipment. It also acts as the UK`s authorisation authority for the re-entry system warhead. By the U.K.
Atomic Energy Authority, responsible for the UK`s design The warhead is located at Aldermaston Atomic Weapons Research Establishment (AWRE), under the direction of the Department of Aviation. The Zuckerman mission found the OPS useful and accommodating, but there was a big shock. The British were to contribute to the research and development costs of the A3, which were postponed until 1 January 1963. They were expected to overflow $700 million by 1968.  Skybolt had been offered to the UK at a unit cost, with the US bearing the costs of research and development, but no such agreement had been reached in Nassau for Polaris. Thorneycroft was afraid of the prospect of paying research and development costs, but McNamara said the U.S. Congress would not defend a deal that put all the burden on the U.S.  Macmillan ordered the U.K. ambassador to the U.S., Sir David Ormsby-Gore, to inform Kennedy that Britain was not prepared to commit to sharing the costs of research and development indefinitely, but would pay an additional 5% for each missile as a compromise. He asked Kennedy to be informed that a failure of the Nassau Agreement would likely lead to the fall of his government.  Ormsby-Gore met with Kennedy on the 12th day, and while Kennedy found that the 5% offer “was not the most generous offer he had ever heard of,” he accepted it.
McNamara, who was sure the U.S. was ripped off, calculated the 5 percent not only on the missiles, but also on their fire control and navigation systems, adding to the bill about £2 million.