Mis-filed (as Arthur Marshall) in the MAR section of the WW1 Service Records (WO 363):

Marshall ARTHUR joined up in May 1915, declared age 36y, born St Stephens.
Home address: Foxhole, St Austell, Cornwall
Married St Austell, 1899 - Kate BRAY.
Children: Launcelot 1900, Ralph 1901, Louisa 1903, Lilian Grace 1906, Marshall Everett 1908, Katie Irene 1915.

Served with the Royal Engineers until discharge 1919. Regt No: 98239. Military Medal 1917.

NB: First Name: GRO Birth = MARSHEL; GRO Marriage = MARSHALL

Anc****y, MAR, pages 3031-3077 (mis-file page 3073)