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
Premiership of Margaret Thatcher 1989, Lawson and Foreign Secretary Geoffrey Howe forced Thatcher to agree to the circumstances under which she would join the Exchange Rate Mechanism. At the meeting, they both threatened they would resign if their demands were not met. Thatcher responded by moving Howe to Leader of the House of Commons (despite giving him the title Deputy Prime Minister he was now effectively removed from decision-making over Europe) and by listening more to her adviser Sir Alan Walters on economic matters. Lawson resigned that October, feeling that Thatcher had undermined him. Thatcher continued to be the leading international advocate of a