Hugh Gaitskell (1906-1963) was leader of the British Labour Party and Leader of the Opposition from 1955 to 1963, when his untimely death allowed Harold Wilson to win the party leadership and, a year later, the office of Prime Minister. Gaitskell had previously served as Minister of Fuel and Power and as Chancellor of the Exchequer in the Labour government of Clement Attlee, whom he succeeded as party leader. Gaitskell was identified strongly with the right wing of the Labour Party, and much of his time as party leader was taken up with policy disputes with the party's left wing or 'Bevanites', led by Aneurin Bevan.
Gaitskell's centrist stance resembled that of the moderate Conservative politician Rab Butler. In consequence, the centrist tendency in British politics, which held sway from the end of the Second World War to the victory of Margaret Thatcher in 1979, was dubbed "Butskellism".