Sydney entered the war in France on the 27th August 1915. He was awarded the Military Medal, and gained promotion to the rank of Corporal, for his actions at Battle of Asiago Plateau in Italy on the 15th June 1918. A citation for his MM, which was published in the Times, dated October 24th 1918, reads: "Corporal Kay was responsible for the evacuation of casualties from the regimental aid posts of the two right battalions. Under an intense bombardment of gas shells and high explosives, which destroyed the roads and necessitated a difficult carry of a mile, often across the open, Corporal Kay worked continuously until the aid posts were clear of wounded.
His splendid example encouraged his fellow bearers and his resource saved many lives." The citation was signed by Lt/Col E.F.Faulkner. He was demobilized in February 1919. Sydney also served in H.M. Services during WW2 as a 2nd Lieutenant in the Home Guard. [Information sources: MICs and family]