Duncan began his career with St Mirren F.C. At some point, he moved to Celtic F.C. where he won the 1909-1910 league championship.Scotland - Championship Winning Teams 1900-1920 He also played for Airdrieonians He then moved to the United States where in 1915, he signed with Bethlehem Steel of the National Association Football League. Duncan and his teammates won the 1915 National Challenge Cup."Bethlehem Champs Of United States". (May 2, 1915). Philadelphia Inquirer, p.64 col.1 He would go on to win the Cup another three times with Bethlehem, in 1916, 1918 and 1919.U.S. Open Cup Medal Winners In 1919, Duncan was part of the Bethlehem Steel tour of South America.Team Will Visit Brazil; New York Times; 20 July 1919 In 1922, he joined Fall River United in the American Soccer League. He played only three games with the team before retiring, but not before playing against the Dick, Kerr Lady Soccer Team.
