Hi Fellow Crighton,
Welcome to Rootschat! If your g grandfather fought in WWI it's very possible that he would appear in the 1901 census. I've found 3 Samuel CRIGHTONs in the 1901 census, 2 of whom would have been of the right age to have fought in WWI:
Samuel CRIGHTON, Living in Bootle, Lancashire, aged 10, born Seacomb, Cheshire, Father: Richard C CRIGHTON (born Liverpool)
Samuel CRIGHTON, Living in Bournmouth, aged 11, born Portsmouth, Father: George CRIGHTON (born Kent)
Could either of these be your g grandfather?
The National Archives site (
www.nationalarchives.gov.uk) has 2 WWI campaign medal cards for Samuel CRIGHTON, one from the Argyl & Southern Highlanders and one from the Army Service Corps, Cheshire Regiment Territorial Force.
Regards,
Al