Which year did Margaret Thatcher become Prime Minister in Great Britain?

Explanation

The Conservative politician Margaret Hilda Thatcher (born 1925) became a Member of Parliament (MP) in 1959, and later served as Education Minister before becoming Prime Minister of Great Britain 1979-1990. She earned the nick name 'the iron lady' because of her unwillingness to compromise. Her triumphs include the victory in the Falklands War between Argentina and Great Britain in 1982. Thatcher left Parliament in 1992, and is now a Member of the Lords.