Born 10 December 1861 at 21 Harewood Square, London, W, the second child of Sidenham Duer, civil engineer, and Mary S Unwin, his. wife. He was educated at St Marylebone and All Souls Grammar School, Regent's Park, under the headmastership of A H Barford, BA, FLS, and at University College Hospital. He then entered the Indian Medical Service and was gazetted surgeon on 28 July 1901, surgeon-major on 28 July 1903, and lieutenant-colonel on 28 July 1911, retiring from the service on 29 November 1911. During this period he was employed as civil surgeon in Rangoon, Maymyo, and Simla. He rejoined the IMS during the war on 17 October 1914 and served until 13 May 1919, acting as surgeon and anaesthetist for the Indian troops at Brighton. He married Caroline Jane Blackstock about 1898 and by her had one son. He died at Hyères, Var, France on 29 November 1937 and was buried there.