Premiership of Margaret Thatcher that Thatcher proceed cautiously in working with black communities because she believed they gave cannabis to babies. 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
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: