Harold Wilson was appointed Prime Minister of the United Kingdom by Queen Elizabeth II on 16 October 1964 and formed the first Wilson ministry, a Labour government, which held office with a thin majority between 1964 and 1966. In an attempt to gain a workable majority in the House of Commons, Wilson called a new election for 31 March 1966, after which he formed the second Wilson ministry, a government which held office for four years until 1970.