The first woman to serve as the British Prime Minister was Margaret Thatcher. She held office from May 4, 1979, to November 28, 1990, becoming the leader of the Conservative Party and the first female head of government in the UK. Thatcher's leadership style and policies, often referred to as "Thatcherism," emphasized privatization, deregulation, and reducing the power of trade unions. Her tenure marked significant political and economic change in Britain, as she aggressively pursued policies aimed at revitalizing the economy, often leading to deep divisions in British society. Thatcher remains a polarizing figure in UK politics and history.