James Alexander Lawson Duncan (1899-30 September 1974) was a Scottish army officer and Conservative Party politician who was briefly active in local government in London. The only child of Alexander Lawson Duncan of Jordanstone, and Margaret nee Dawson. Following education at the University of Cambridge he received a commission in the Scots Guards in 1917 and saw service at the Western Front in the closing stages of the First World War. In 1920 he was released from the army and moved to Northern Rhodesia where he had a large farm.