There is a J Tennyson listed in the Commonwealth war graves site. He died on the 6 January 1918 aged 24. He was serving with the 6th Bn Royal Enniskilling Fusiliers. He was the son of James and Anne Tennyson. He is buried in Benfieldside Cemetry, Consett, Co Durham. This suggests to me that he wasn't killed in action but died from injuries received prior to being brought back to this country. Sorry I can't help more.