Murdoch was conscripted into the Royal Air Force in 1941, serving as a pilot officer in the intelligence section of Bomber Command, before being posted to the Department of Allied Air Force and Foreign Liaison as a Flight Lieutenant. In 1943 he joined the Directorate of Administrative Plans at the Air Ministry, where he shared an office with Wing Commander Kenneth Horne, being responsible for the supply of aircraft and air equipment to Russia. He finished the war with the rank of Squadron Leader. Horne and Murdoch quickly became friends and as both were regular broadcasters they invented a fictitious RAF station Much Binding in the Marsh for a programme of the same name. It went on air in January 1944, and when peace came in 1945 it became a civilian airport and the show continued successfully; the last programme was in March 1954.