In which year did Margaret Thatcher resign as Prime Minister of Great Britain and Northern Ireland?

Margaret Hilda Thatcher, Baroness Thatcher, (née Roberts; 13 October 1925 – 8 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'.

Mrs Thatcher was elected Member of Parliament for Finchley in 1959. Edward Heath appointed her Secretary of State for Education and Science in his Conservative government. In 1975, Thatcher defeated Heath in the Conservative Party leadership election to become Leader of the Opposition, the first woman to lead a major political party in the United Kingdom. She became Prime Minister after winning the 1979 general election.

She was re-elected for a third term in 1987, but her subsequent support for the Community Charge ("poll tax") was widely unpopular, and her views on the European Community were not shared by others in her Cabinet. This led to dissatisfaction with her leadership amongst her colleagues. She resigned as Prime Minister and Conservative Party leader in November 1990, after Michael Heseltine successfully launched a challenge to her leadership.

In 2013, she died of a stroke in London at the age of 87.