Merseyman, two possible routes for you.
1. The Army keep service records themselves, you say you have some of his service papers, are these from the Army?, if not write to them with your enquiry.
2. The national archives at Kew in London have many historical records, almost all of the various Government departments, including the services,official papers. (note of caution here, I dont know if Scottish records are kept there), a visit to their website will tell you more.
hope you find out what you are looking for.