Margaret Thatcher was the first female British Prime Minister. The leader of the Conservative Party, she won three consecutive terms of office (the only British PM in the twentieth century to do so), transformed the nation and at the time was the longest serving PM since 1827, governing from 1979 - 90. She was also the most divisive PM of the century, earning both great reverence but also deep hatred from the divided public, particularly for her treatment of trade unions.