Sidney Giles was a resident of Herne Hill, living at 40 Fawnbrake Avenue. He was the youngest of the five children of Herbert and Martha Giles, who in 1911 were aged 63 and 59 respectively. The family was living at 77 Lilford Road, Camberwell, at that time. Herbert was a carpenter, a trade two of his four sons pursued. Sidney was a boy clerk at the Admiralty in 1911, and Percy his closest brother in age was an insurance clerk. Their only sister, Martha, was a clerk working for a brewery. The Gileses had another five children, who by then were all deceased.

Sidney was a Lance Corporal in the 14th Battalion (London Scottish) of the London Regiment. He fought in the war from January 1916 and was killed in action on the first day of Battle of the Somme, 1 July 1916, aged just 22. He is commemorated on the Thiepval Memorial and his name is also on the St Paul's Memorial Screen in Herne Hill.