Margaret Thatcher Foundation in 2006, where she established the Margaret Thatcher Center for Freedom. Margaret Thatcher Margaret Hilda Thatcher, Baroness Thatcher, (; 13 October 19258 April 2013) was a British stateswoman who served as Prime Minister of the United Kingdom from 1979 to 1990 and Leader of the Conservative Party from 1975 to 1990. She was the longest-serving British prime minister of the 20th century and the first woman to hold that office. A Soviet journalist dubbed her "The 'Iron Lady, a nickname that became associated with her uncompromising politics and leadership style. As Prime Minister, she implemented policies known as Thatcherism.
Premiership of Margaret Thatcher her opposition to greater economic integration into the European Community. She also alienated many Conservative voters and Members of Parliament with the imposition of the local poll tax. As her support fell away, she was challenged for the party leadership and persuaded by her Cabinet to withdraw from the second round of voting, ending her eleven-year tenure as Prime Minister. Though she remains a domestically polarising figure, historians and political scientists generally rank Thatcher as an above-average Prime Minister. Biographer John Campbell reports that in July 1978 when asked by a Labour MP in Commons what she meant by socialism: