Percy was born in Godalming on 30 March 1893, the son of Charles and Elizabeth Windybank. The family lived in Peper Harrow in 1901 and in 1911 at 4, Northfields, Witley. At the time of his enlistment in the Hampshire Regiment in 1915 Percy was a footman at Chelsworth Hall, Ipswich. After the war the family moved to Ashstead.
The Machine-Gun Corps (MGC) was created in 1915 from the machine-gun sections of the infantry regiments. 88th MGC was formed in February 1916 in Suez following the withdrawal from Gallipoli and went to France in March 1916, taking part in the Somme Campaign (July – October 1916) and Le Tresloy of January and February 1917. Percy was gazetted for the Military Medal in the London Gazette of 3 March 1917 and the Witley All Saints’ Parish Magazine records on 27 January 1917 that this was for gallantry in an “unknown part of France” (probably during the fighting at Le Tresloy). Percy was killed in action on 23 April 1917 during the Second Battle of Scarpe (part of the Second Battle of Arras). He has no known grave so his body may not have been recovered or not identified. He is commemorated on the Arras Memorial and is also commemorated on the memorial in St Luke’s Church, Milland. Percy’s father volunteered for the Royal Army Veterinary Corps in 1915. As well as the Military Medal Percy was awarded the British War Medal and the Victory Medal.