Third Thatcher ministry to make way for a leader more likely to win the next general election. Her successor was the Chancellor of the Exchequer John Major, who was elected on 27 November 1990, and who at 47 became the youngest Conservative Prime Minister of the 20th century. <section begin="June 1987 to July 1989" /> <section begin="July 1989 to November 1990" /> Members of the Cabinet are in bold face. Third Thatcher ministry Margaret Thatcher was Prime Minister of the United Kingdom from 4 May 1979 to 28 November 1990, during which time she led a Conservative government. She was the first woman
Deputy Prime Minister of the United Kingdom Tyne. William Whitelaw was Margaret Thatcher's "de facto" deputy from 1979–1988, an unofficial position he combined with that of Home Secretary in 1979–1983 and Leader of the House of Lords after 1983. Sir Geoffrey Howe was bestowed the title of Deputy Prime Minister by Thatcher in 1989, on being removed from the post of Foreign Secretary. He resigned as her deputy in 1990, making a resignation speech that is widely thought to have hastened Thatcher's downfall. Thatcher's successor John Major did not appoint a Deputy Prime Minister until 1995, when Michael Heseltine was given the post. John Prescott, who was