Britain's youngest Prime Minister was William Pitt, who served from 1783 to 1801. He was only 24 years old when he became Prime Minister, making him the youngest person to ever hold the office. Pitt was a prominent figure in British politics during the late 18th century and is widely regarded as one of the greatest statesmen in British history. He is credited with introducing numerous reforms to the British government, including the introduction of income tax and the abolition of slavery.