Headlam served as Officer Commanding North-Western Area in 1946, and as Director of Training from 1947 to 1950. In 1950–51, during the Malayan Emergency, he was stationed at Singapore as commander of No. 90 (Composite) Wing and, later, RAF Tengah. He twice served as acting Air Member for Personnel, in 1957 and 1959–60, receiving appointment as a Commander of the Order of the British Empire in 1958. Promoted air vice marshal, he successively held the positions of Air Officer Commanding (AOC) Operational Command in 1961–62, AOC No. 224 Group RAF from 1962 to 1965 during the Indonesia–Malaysia "Konfrontasi", Deputy Chief of the Air Staff in 1965–66, and AOC Support Command in 1966–67. He was appointed a Companion of the Order of the Bath in 1965. Following a posting to London as Head of the Australian Joint Services Staff from 1968 to 1971, he retired from the Air Force and died in Melbourne five years later.