Edward George Geoffrey Smith-Stanley, 14th Earl of Derby, KG GCMG PC PC (Ire) (29 March 1799 – 23 October 1869, known before 1834 as Edward Stanley, and from 1834 to 1851 as Lord Stanley) was a British statesman, three-time Prime Minister of the United Kingdom and, to date, the longest-serving leader of the Conservative Party. He was a scion of one of Britain's oldest, wealthiest and most powerful families. He is one of only four British prime ministers to have three or more separate periods in office. However, his ministries each lasted less than two years and totalled three years and 280 days. Derby introduced the state education system in Ireland, and reformed Parliament.