1990
Margaret Thatcher who had been the United Kingdom's Prime Minister since 1979 resigned as Prime Minister on November 22nd 1990
Thatcher's tenure as Prime Minister was the longest since that of Lord Salisbury and the longest continuous period in office since Lord Liverpool 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 hold 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 entitles her to sit in the House of Lords.