Margaret Hilda Thatcher, Baroness Thatcher, LG, OM, DStJ, PC, FRS, HonFRSC 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. 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 that have come to be known as Thatcherism.
A research chemist at Somerville College, Oxford, before becoming a barrister, 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.