Mosley, Sir Oswald Ernald (mōzˈlē) [key], 1896–1980, British fascist leader. He entered (1918) Parliament as a Conservative, became (1922) an independent, and then joined (1924) the Labour party. He was junior minister in the Labour government of 1929 but resigned (1930) when the cabinet rejected his economic proposals. In 1931 he founded another socialist party, the New party, but it received little support, and Mosley began to drift toward fascism. He organized (1932) the British Union of Fascists, modeled upon the German and Italian fascist parties.
Married first to Lady Cynthia Curzon, daughter of Lord Curzon, after her death he married (1936) his mistress, Diana Mitford Guinness (1910–2003), sister of the writers Jessica and Nancy Mitford. Diana and another sister, Unity Freeman-Mitford, were friends of Hitler. Until after the outbreak of World War II, Mosley conducted a speech-making campaign of vilification and abuse, directed largely against the Jews. In 1940 he and his wife were interned. They were released in 1943. After the war Mosley attempted to revive his movement. As an unsuccessful candidate in the election of 1959 he called for an end to nonwhite immigration.
See his autobiography, My Life (1968); biographies by R. Skidelsky (1975) and D. S. Lewis (1987); D. R. Shermer, Black Shirts: Fascism in Britain (1971); biography of Diana Mosley by J. Dailey (2000).