Margaret Thatcher ( 13 October 1925 – 8 April 2013) was a British stateswoman and Conservative politician who was 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 the position. As prime minister, she implemented economic policies known as Thatcherism. A Soviet journalist dubbed her the "Iron Lady", a nickname that became associated with her uncompromising politics and leadership style.