Project Emily was the deployment of American-built Thor intermediate-range ballistic missiles (IRBMs) in the United Kingdom between 1959 and 1963.

Due to concerns over the buildup of Soviet missiles, US President Dwight D. Eisenhower met Prime Minister Harold Macmillan in Bermuda in March 1957 to explore the possibility of short-term deployment of IRBMs in the United Kingdom until the long-range intercontinental ballistic missiles (ICBMs) were deployed.

The first Thor missile arrived in the UK on a Douglas C-124 Globemaster II transport aircraft in August 1958, and was delivered to the RAF in September.

During the early part of the Second World War, Britain had a nuclear weapons project, codenamed Tube Alloys.

[1] At the Quebec Conference in August 1943, the Prime Minister of the United Kingdom, Winston Churchill and the President of the United States, Franklin Roosevelt, signed the Quebec Agreement, which merged Tube Alloys with the American Manhattan Project to create a combined British, American and Canadian project.

Its control of "restricted data" prevented the United States' allies from receiving information related to nuclear weapons.

[4] Fearing a resurgence of United States isolationism, and Britain losing its great power status, the British government restarted its own development effort,[5] which was codenamed High Explosive Research.

[12] In March 1954 the Ministry of Supply was asked to put forward proposals for a full-scale ballistic missile project.

[10] At a NATO meeting in Paris in December 1953, the United States Secretary of Defense, Charles E. Wilson, raised the possibility of a joint development programme with the Minister of Supply, Duncan Sandys.

[15] In parallel to the ICBM programme, the United States developed three separate intermediate range ballistic missile (IRBM) systems.

[16] The Army Ballistic Missile Agency, commanded by Major General John B. Medaris, with Wernher von Braun as its technical director, developed the Jupiter (SM-78) IRBM.

[22] Britain, Germany, Turkey, the Philippines, Taiwan, South Korea and Japan were considered as possible sites for them.

[16] Gordon Gray, the US Assistant Secretary of Defense for International Security Affairs, mentioned it to a Ministry of Supply official in January 1956,[23] and unofficial, low-level approaches began in March 1956.

[26] The missiles could be fitted with British warheads, but these would be heavier, reducing the range to 1,250 nautical miles (2,320 km; 1,440 mi).

[27] The Chairman of the Chiefs of Staff Committee, Marshal of the Royal Air Force Sir William Dickson, queried whether Blue Streak was redundant if the Americans supplied Thor.

Like many senior RAF officers and their USAF counterparts, he was also concerned about the fate of the manned bomber if the government embraced missile technology.

[28] A precedent here was Project E, under which data on US nuclear weapons was supplied to Britain to allow English Electric Canberra bombers and V-bombers to carry them in wartime.

[31] The Prime Minister, Harold Macmillan, and President Dwight D. Eisenhower agreed to do so at a summit in Bermuda in March 1957.

The British saw the IRBMs as a step on the path to an independent nuclear deterrent, while the Americans saw it as an augmentation of the Strategic Air Command (SAC).

[35] It placed the Eisenhower administration under great public pressure to act on the deployment of missiles by a shocked and distraught nation.

The proposal to base USAF Thor squadrons in Britain was dropped on 12 October 1957 in view of the British political opposition.

[37] A formal agreement was drawn up on 17 December 1957, although it was not until the end of the month that it was definitely determined that Britain would receive Thor and not Jupiter missiles.

[39] The practical difficulty with US custody of the warheads was that if they were all stored at RAF Lakenheath in Suffolk, it would take up to 57 hours to make the missiles operational.

The main selection criterion was the condition of the road network connecting the bases; a grade of more than one in seventeen was considered an unacceptable risk of grounding the missile transport.

Despite the fact that a Thor missile had exploded on the launch pad just a few days before, the launch was viewed by dignitaries including Brigadier Godfrey Hobbs, the Director of Public Relations at the Ministry of Defence; Air Vice-Marshal Walter Sheen, the RAF commander at the British Joint Staff Mission; and Air Vice-Marshal Augustus Walker, the commander of No.

The dual key system was thereby put under strain due to the RAF and USAF personnel being on different states of readiness.

[86][87] Under the war plan that had gone into effect on 1 August 1962, the RAF's bombers and Thor missiles targeted 16 cities, 44 airfields, 10 air defence control centres and 20 IRBM sites.

With ICBMs becoming available, the Americans did not foresee the Thor missiles making a substantial contribution to the western nuclear deterrent after 1965.

The future of the British strategic nuclear deterrent now lay with the Royal Navy,[94] and the last Thor squadrons were inactivated on 23 August 1963.

[95] The Thor missiles were flown back to the United States, and refurbished at the Douglas Aircraft plant in Tulsa, Oklahoma.