British Prime Ministers are the heads of the UK government, responsible for overseeing the operation of the government and making policy decisions. They are usually the leader of the political party that has the most seats in the House of Commons. The Prime Minister is appointed by the Monarch and plays a key role in shaping national and international policies. The position of Prime Minister has existed since the early 18th century, evolving over time. Notable Prime Ministers include Winston Churchill, known for his leadership during World War II, and Margaret Thatcher, the first female Prime Minister, who served from 1979 to 1990.