Margaret Thatcher, the first female Prime Minister of the United Kingdom, was born on 8 December 1915 and passed away on 4 July 2010 at the age of 87. She served as PM from 1979 to 1990, making her the longest-serving British Prime Minister of the 20th century. During her time in office, Thatcher advocated policies of privatization, deregulation and reduction of trade union power which had a significant impact both domestically and internationally.