These diplomatic missions represent the UK during negotiations and ensure Britain's interests and views are taken into account by UN bodies and other member states.

On 12 June 1941, representatives of the United Kingdom, Canada, Australia, New Zealand, the Union of South Africa, and of the exiled governments of Belgium, Czechoslovakia, Greece, Luxembourg, Netherlands, Norway, Poland, and Yugoslavia, as well as General de Gaulle of France, met in London and signed the Declaration of St James's Palace.

[10] The two main principles of these agreements, a commitment to mutual assistance and renunciation of a separate peace, formed the basis for the later Declaration by United Nations.

During the visit, Roosevelt coined the name "United Nations" and suggested it to Churchill to refer to the Allies of World War II.

Churchill accepted the idea noting the phrase was used by Lord Byron in the poem Childe Harold's Pilgrimage, which referred to the Allies at the Battle of Waterloo in 1815.

After months of planning, the UN Conference on International Organization opened in San Francisco in April 1945 attended by 50 governments and a number of non-governmental organisations involved in drafting the United Nations Charter.

The heads of the delegations of the four sponsoring countries (the U.S., the U.K., the Soviet Union, and China) invited the other nations to take part and took turns as chairman of the plenary meetings beginning with Anthony Eden of Britain.

[21] The UN officially came into existence on 24 October 1945 upon ratification of the Charter by the five permanent members of the Security Council—the U.S., the U.K., France, the Soviet Union and the Republic of China—and by a majority of the other 46 signatories.

[28] Along with France, the United Kingdom used its power to veto a draft resolution aimed at resolving the Suez Canal crisis in 1956.

[30] According to a formal statement made jointly by the United Kingdom and France in 2008: Reform of the UNSC, both its enlargement and the improvement of its working methods, must therefore succeed.

United Nations Security Council Resolution 1244 authorised the NATO-led Kosovo Force beginning in 1999 in which the UK played a leading role at the outset.

Acting under United Nations Security Council Resolution 1973 in 2011, the UK and other NATO countries intervened in the Libyan Civil War.