Neil John Gahan was born on 20 September 1916 at Ivanhoe, Victoria to Walter Ernest and Alice Miriam (née Rourke) Gahan. He was raised in Melbourne with his family. Gahan became a bank officer and served in the local militia.

Gahan enlisted in the Second Australian Imperial Force on 14 November 1940 at Royal Park, Victoria. He married Heather Penney at the Melbourne Grammar School Chapel on 19 July 1941, only eleven days before departing Australia to serve with the 2/29 Australian Infantry Battalion in Malaya. In early 1942, Gahan became a prisoner of war of the Japanese, alongside many other members of the 2/29 Australian Infantry Battalion. He was interned at Changi and sent to work on the Burma-Thai Railway as part of “F Force”.

After the war, Gahan returned to Australia, worked as a bank clerk, and lived with Heather at Essendon North, Victoria. In 1958, they were living in Killara, New South Wales and, after moving several times, they settled in the suburb of Seaforth, New South Wales in 1968. As they got older, the couple moved to Caloundra, Queensland. Neil John Gahan died on 7 August 1995.