This man enlisted as MARR, so is mis-filed in the WW1 Service Records (WO 363):

James DEAN enlisted (as James MARR) with the RGA on 17 October 1914, declaring age 31y 1m, born Gateshead. (Probably born Newcastle 1882).
Served as Pte 47964 until Killed In Action 31 May 1917.
Awarded the Military Medal (presumably posthumously - it appears to have been presented to his regiment rather than his widow?).

Home address: Byker, Newcastle.
Mother: Ann.
Brothers: William (c1887), Andrew (c1889), Walter (c1891) & Thomas (c1895).
Sisters: Mrs Nellie PILKINGTON (c1885) living in Brisbane, Australia by 1920, & Norah (c1893).

Married Margaret YOUNG in Newcastle in 1905 (she re-married a Patrick HANRATTY in 1919).
Children: Matthew 1905, William 1907, Margaret Ellen 1908 & John 1911.

Anc****y, MAR, pages 82346-82375