A Conservative Party leadership election in the United Kingdom took place on 20 November 1990 following the decision of Michael Heseltine, former defence and environment secretary, to challenge Margaret Thatcher, the incumbent prime minister, for leadership of the Conservative Party.

In the months leading up to the contest, Thatcher's position was slipping due to her increasingly divisive and confrontational approach in the United Kingdom. Her Community Charge had proven to be highly unpopular and resulted in widespread riots across the country, while her Euroscepticism had begun to become a detriment to the Conservatives. The economy, which was booming, had started to enter the early stages of a recession due to high inflation. The tipping point came in October when Thatcher infamously refused the European Community's plans for further integration, prompting her longest serving minister Geoffrey Howe to resign. Immediately following his resignation, Heseltine challenged Thatcher to a contest in November.

Thatcher failed to win outright on the first ballot, missing the threshold by just 4 votes, and was persuaded to withdraw from the second round of voting to avoid a potential defeat. She announced her resignation on 22 November 1990, ending more than 15 years as Conservative leader and 11 years as Prime Minister.



The prime minister of the United Kingdom is the head of government in the United Kingdom. The prime minister advises the sovereign on the exercise of much of the royal prerogative, chairs the Cabinet and selects its ministers. As modern prime ministers hold office by virtue of their ability to command the confidence of the House of Commons, they sit as a member of Parliament.

The office of prime minister is not established by any statute or constitutional document, but exists only by long-established convention, whereby the reigning monarch appoints as prime minister the person most likely to command the confidence of the House of Commons; this individual is typically the leader of the political party or coalition of parties that holds the largest number of seats in that chamber. It was announced by Prime Minister Boris Johnson on 31 January 2022 that the office of Prime Minister would be formally established.The prime minister is ex officio also First Lord of the Treasury, Minister for the Civil Service and the minister responsible for national security.: p.22  Indeed, certain privileges, such as residency of 10 Downing Street, are accorded to prime ministers by virtue of their position as First Lord of the Treasury. In 2019, the office of Minister for the Union was established; Boris Johnson became the first prime minister to hold this title.