Walter Leslie Duncan

Walter Leslie Duncan (14 February 1883 – 28 May 1947) was an Australian politician and trade unionist. He was a Senator for New South Wales from 1920 to 1931.

Duncan was born in Armidale, New South Wales. He moved to Sydney after leaving school and worked as a clerk and accountant, becoming involved in the labour movement. He served as president of the Clerks' Union and briefly as president of the Labor Council of New South Wales, also standing twice in state elections for the Australian Labor Party (ALP). During World War I, Duncan sided with Prime Minister Billy Hughes during the ALP split over conscription and subsequently joined Hughes' new Nationalist Party. He enlisted in the Australian Imperial Force in 1917 and served overseas for several months with the 17th Battalion.

Duncan was elected to the Senate on the Nationalist ticket at the 1919 federal election, campaigning as a returned soldier. He served as a government whip from 1925 to 1926 and was re-elected to a second term at the 1925 election. Duncan continued to ally himself with Hughes in parliament, frequently crossing the floor. After Hughes and his supporters precipitated the collapse of the Bruce–Page government in 1929, Duncan was expelled from the Nationalists and joined Hughes' new Australian Party, which merged into the United Australia Party in 1931. He resigned from the Senate in 1931 after losing UAP preselection and made several unsuccessful attempts to re-enter parliament.