John Leslie was a son of Robert and Margaret Leslie. John was born on 1st February 1893 in Castledawson, Magherafelt. The family moved to Antrim around 1898. His father was a linen weaver. Both John and his sister, like their father, were employed as linen weavers. Private John Leslie was serving with the 8th Battalion of the Seaforth Highlanders when he was killed in action in France on Saturday 25th September 1915. By 1916 the family have moved back to Magherafelt.
Loos-en-Gohelle is a village 5 kilometres north-west of Lens, and Dud Corner Cemetery is located about 1 kilometre west of the village, to the north-east of the N943, the main Lens to Bethune road.