Margaret Hilda Thatcher, Baroness Thatcher (13 October 19258 April 2013) was a British stateswoman. She served as Prime Minister of the United Kingdom (UK) from 1979 until her resignation in 1990, longer than any other British prime minister in the 20th century. She led the UK's Conservative Party from 1975 to 1990. Thatcher was the first female British prime minister and was often known by the nickname "The Iron Lady", given to her by a journalist from the Soviet Union. Her birth name was Margaret Hilda Roberts.