Turner was commissioned as a second lieutenant on 3 January 1916 to serve in the Royal Flying Corps, and after completing his flight training, he was appointed a flying officer and confirmed in his rank on 17 June. He was promoted to lieutenant on 1 March 1917, and on 7 May was appointed a flight commander with the temporary rank of captain. Turner gained his first aerial victories on 13 August 1917, while serving in No. 55 Squadron, flying an Airco DH.4 two-seater day bomber. With Second Lieutenant R. Brett as his observer, he drove down out of control two Albatros D.V fighters over Roulers. On 26 September 1917 he was awarded the Military Cross, the citation for which was eventually published on 8 January 1918. It read: On 1 April 1918, the Army's Royal Flying Corps and the Royal Naval Air Service were merged to form the Royal Air Force. Turner, now serving in No. 57 Squadron marked the occasion by shooting down three Fokker Dr.I fighters over Irles, with Second Lieutenant A. Leach as his observer, taking his total to five and making him an ace. On 28 July he shared with the crews of two other aircraft in the driving down of a Fokker D.VII fighter over Vaulx-Vraucourt, with Sergeant S. G. Sowden as his observer, and on 8 August he and observer Second Lieutenant H. S. Musgrove destroyed another D.VII over Moislains Airfield, to bring his total to seven. Turner was subsequently awarded the Distinguished Flying Cross, which was gazetted on 1 November 1918. His citation read: Turner eventually relinquished his RAF commission on 12 March 1920, due to ill-health contracted on active service, and was permitted to retain his rank.
List of aerial victories
Inter-war career
After the war Turner turned to an academic career, graduating from Magdalene College, Cambridge, and winning the La Bas Prize in 1924 for his essay The Element of Irony in English Literature, which was published in 1926, and then becoming a fellow of the college.
World War II
Turner returned to military service during the Second World War, being commissioned as a pilot officer "for the duration of hostilities" in the Administrative and Special Duties Branch of the Royal Air Force Volunteer Reserve on 31 October 1940. He was promoted to the war substantive rank of flying officer on 27 May 1941, and was appointed a temporary squadron leader on 1 July 1944. He resigned his commission on 4 November 1944, retaining the rank of squadron leader.
Post-war career
Turner returned to Magdalene, eventually becoming Pepys Librarian and President of the College. His contemporaries included Dennis Babbage and C. S. Lewis, and he became a close friend of T. S. Eliot. Turner died in Chichester, West Sussex, on 18 June 1982.