Premiership of Margaret Thatcher Premiership of Margaret Thatcher Margaret Thatcher served as Prime Minister of the United Kingdom from May 1979 to November 1990. She became Prime Minister after serving as Leader of the Conservative Party since 1975. In domestic affairs, Thatcher is best known for her sweeping policies concerning the affairs of the economy, including the privatisation of most nationalised industries. In foreign policy, she fought a war against Argentina and played a key role with President Ronald Reagan and Soviet leader Mikhail Gorbachev in ending the Cold War. By the late 1980s, she was alienating many senior members of her Cabinet by
Margaret Thatcher on and fight to win" the second ballot, but consultation with her Cabinet persuaded her to withdraw. After holding an audience with the Queen, calling other world leaders, and making one final Commons speech, on 28 November she left Downing Street in tears. She reportedly regarded her ousting as a betrayal. Her resignation was a shock to many outside Britain, with foreign observers such as Henry Kissinger and Gorbachev privately expressing consternation. Thatcher was replaced as Prime Minister and party leader by Chancellor John Major, who prevailed over Heseltine in the subsequent ballot. Major oversaw an upturn in Conservative support