Her Majesty's Diplomatic Service (HMDS) is the diplomatic service of the United Kingdom of Great Britain and Northern Ireland, dealing with foreign affairs, as opposed to the Home Civil Service, which deals with domestic affairs. It employs around 14,000 people, roughly one-third of whom are crown servants working directly for the Foreign and Commonwealth Office, either in London or abroad. The remaining two thirds of staff are employed locally by one of nearly 270 British diplomatic missions abroad (such as embassies, consulates or high commissions).^[1] The Permanent Under-Secretary of State for Foreign Affairs is also the Head of the Diplomatic Service.

The Foreign Service, which originally provided civil servants to staff the Foreign Office, was once a separate service, but it amalgamated with the Diplomatic Service in 1918. The Diplomatic Service also absorbed the Colonial Service in the late 1960s.

Women were not allowed to join the Diplomatic Service until 1946. Until 1973, they were required to leave when they married. The first female ambassador to be appointed was Barbara Salt, to Israel in 1962, but ill-health prevented her from taking up the post. The first woman to serve as an ambassador was Anne Warburton, appointed to Denmark in 1976.^[2]