Born in Bothwell, Tasmania,[1] Headlam was a left handed batsman and slow left arm orthodox bowler and played one first-class match for Tasmania in 1911/12, achieving a highest score of 32 not out.

[1] During World War I, Headlam served in the Australian Army, enlisting on 14 April 1915 and returning to Australia on 4 March 1919, reaching the rank of lieutenant.

[2] He initially served with the 3rd Light Horse Regiment and embarked with their 6th reinforcements as a trooper for service overseas on 17 June 1915, departing Melbourne on HMAT Wandilla.

[3] He joined his unit at Gallipoli in October 1915 and served on the peninsula until the Australians were evacuated in December.

[4][5] Serving in the Middle East,[6] Headlam was initially an air observer,[7] but later qualified as a pilot and took part in the Battle of Meggido in the final stages of the war.