William Ewart Gladstone
His career lasted more than 60 years. He served as Liberal Prime Minister four times. This was more than any other person (1868–1874, 1880–1885, 1886 and 1892–1894). Gladstone was 84 years old when he resigned for the last time. This made him Britain's oldest ever Prime Minister. He served as Chancellor of the Exchequer four times (1853–1855, 1859–1866, 1873–1874 and 1880–1882).