Just 2 sides, dealing with discharge, no clue to age, Mis-filed with Scott in the WW1 Service Records (WO 363):

Joseph BAXTER, home address GREENLAW, Co Berwick.
Embodied January 1915, discharged January 1918 - from St Albans Military Hospital (Pleurisy).
Served with 4th KOSB and 9th HLI. Reg Nos: 350251, 200948, 7682.

Anc****y, SCO, pages 51742 & 51743