Allan Stanley Deacon was Scottish by birth and had been born at Milton on Lenzie, Dunbartonshire, in 1886. He was 29 years old when he enlisted, a single man, who named as his next of kin his father, Cecil Deacon of Kirkintillock, Scotland. Cecil Deacon (1859-19350 and his wife Letitia Frances, nee Berry, (b.1863) were the parents of six children, of whom Allan was the second oldest. He had left England on 23 November, 1912, and in 1915, when he enlisted, he was living at 342 Albert Street, East Melbourne, Victoria.

Allan was an engineer by trade and so was placed in the 5th Company Engineers, raised in Victoria in September, 1915. His unit was the Australian Electrical, Mechanical, Mining and Boring Company. The Unit embarked from Melbourne on board HMAT Ceramic A40 on 27 November, 1915. Presumably they went straight to England, then on to France, but it is difficult from the nature of the engineers' tasks to know eactly where they were, as they were deployed in different areas as the need rose. Included in their tasks were constructing lines fo defence, temporary bridges, tunnels, trenches, observation posts, roads, railways, communication lines, all types of buildings, bathing facilities and sewerage pits and a multitude of other tasks. On  25 September, 1916, Allan Deacon was wounded slightly, but did not appear to have been sent to hospital. On 15 December, he was made Lance Corporal on a temporary basis. He was wounded again, this time in action, on 12 February, 1917. On 3 April, 1917, while in France, he was detached for duty, but there is no description of what that duty was, other than it was with 'A.Clec.,men of BN Unit from 5 7d by Ae ex AGDB' and it is interesting that at this time he reverts at his own request to the rank of sapper. On 21 April, he became ill and was sent back to hospital in France, returning to duty on  9 May. On 8 December, he was again taken on strength with the AEMM+B Company from the 5th Field Engineers.

Allan was wounded again on 2 May 1918 and was again sick on 12 July, 1918. On 20 May, 1919, he was returned to Australia, disembarking in Melbourne on 2 July.   Two months later, he married Beastrice Victoria Nelson at Clifton Hill, Victoria. In 1919, the Electoral Roll has them living at Clifton Hill, but by 1936 they were at Methyr, Brisbane. He made a return visit to England in 1948. Allan Sanley Deacon died, aged 86, at the concocord Repatriation Hospital, Sydney. He and beatrice do not appear to have had children.