Margaret Hilda Thatcher, Baroness Thatcher, LG, OM, PC (born Margaret Hilda Roberts on 13 October 1925) served as British Prime Minister from 1979 to 1990 and leader of the Conservative Party from 1975 until 1990, being the first (and, to date, only) woman to hold either post.
Thatcher was the longest-serving British Prime Minister since Lord Salisbury and had the longest continuous period in office since Lord Liverpool who was prime minister in the early 19th century. She was the first woman to lead a major political party in the UK, and the first of only three women to have held any of the four great offices of state. She currently has a life peerage as Baroness Thatcher, of Kesteven in the County of Lincolnshire, which allows her to sit in the House of Lords.