After returning to Australia in February 1942, Headlam held staff appointments and training commands, finishing the war a group captain.

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.

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.

1 Flying Training School (FTS) at RAAF Point Cook, Victoria, and was commissioned as a pilot officer on 1 January 1935.

1 FTS and operated Supermarine Southampton flying boats and de Havilland Gipsy Moth floatplanes, among other types.

According to Air Force historian Alan Stephens, this paper "in effect, defined the 'anti-lodgment' concept which has been a persistent feature of RAAF strategic thinking".

[6] Commencing in July 1938, he was one of six students to take part in the RAAF's first Long Specialist Navigation Course, run by Flight Lieutenants Bill Garing and Alister Murdoch at Point Cook.

The course involved several epic training flights that attracted considerable media attention, including a twelve-day, 10,800-kilometre (6,700 mi) round-Australia trip by three Avro Ansons, one of which was piloted by Headlam, in November.

[9] Headlam continued to serve with the squadron as a flight commander until 15 January 1940, when he was assigned to Headquarters Laverton as the station navigation officer.

[3][6] Two weeks later he married Katherine Bridge at St Paul's Anglican Church in Frankston; the couple had a son and a daughter.

[3][6] Equipped with Lockheed Hudsons, the squadron mainly conducted maritime patrols in southern waters until 5 December, when four of its aircraft were ordered to Darwin, Northern Territory, in response to fears of Japanese aggression in the Pacific.

[11][12] The following day, aware that Australia was now at war in the Pacific, one of the Penfui-based Hudsons attacked the Japanese pearler Nanyo Maru, which was suspected of being a radio ship, and forced it aground.

The intact Hudsons were withdrawn to Darwin but Headlam and his staff remained at Penfui so the base could be used by aircraft during reconnaissance missions from Australia.

[8][14] On 18 February, Headlam was ordered to evacuate all his personnel except a small party to demolish the airfield with assistance from Sparrow Force.

2 Squadron's Hudsons were destroyed in the attack; the remainder were relocated to Daly Waters, where they continued to carry out reconnaissance and bombing missions against Japanese targets in Timor.

[1] Posted to Britain at the end of the year, he attended the Royal Air Force Staff College, Andover, and served with RAAF Overseas Headquarters, London.

The Dakotas were tasked with courier flights, VIP transport and medical evacuations across South East Asia, and in Malaya with airlifting troops and cargo, dropping supplies to friendly forces and despatching propaganda leaflets.

[24] On 19 February 1952, Headlam became senior air staff officer (SASO) at Eastern Area Command in Penrith, New South Wales.

[26] Headlam was appointed an Officer of the Order of the British Empire (OBE) in the 1954 New Year Honours for his "exceptional ability and devotion to duty".

[6] In November he was posted to RAAF Overseas Headquarters, London, and the following year undertook studies at the Imperial Defence College.

[33] Headlam was appointed a Commander of the Order of the British Empire (CBE) in the 1958 Queen's Birthday Honours, gazetted on 3 June.

[1][37] Divorced from his first wife in 1956, he married widowed social worker Vernon Spence at the Sydney registry office on 20 January 1964.

[1][6] He was appointed a Companion of the Order of the Bath (CB) "in recognition of distinguished service in the Borneo Territories" on 22 June.

[40] His tenure as DCAS coincided with the most significant rearmament program the Air Force had undertaken since World War II, and with manpower shortages stemming from this expansion and from Australia's increasing involvement in the security of South East Asia.

[45] Headlam succeeded Air Vice Marshal Douglas Candy as AOC Support Command, Melbourne, on 8 August 1966.