His service record is on Ancestry. It says that he was aged 40 when he signed up in 1915, which would give him a year of birth of about 1875, but it must be him because his wife is Jane Hallam m 24.10.1896. It also gives names and dobs for 7 children. Have you got Ancestry?
http://search.ancestry.co.uk/iexec/?...rc=&pid=234378
Jackie