The UNP, established by D. S. Senanayake in 1946, was until recently the largest single political party. It is the only political group which had representation in all parliaments since independence. SLFP was founded by S. W. R. D. Bandaranaike in July 1951. SLFP registered its first victory in 1956, defeating the ruling UNP in 1956 Parliamentary election. Following the parliamentary election in July 1960, Sirimavo Bandaranaike became the prime minister and the world's first elected female head of government.