Dear Dave
Hope all's well with you. If you go to /www.nationalarchives.gov.uk or go to The Imperial War museum, they will supply you a list of researchers who will do the search for you for around a fiver. www.iwm.org.uk
Give the researcher as much information as you can, such as full name, regiment if known, number if known and place of birth. A lot of the World War One records were destroyed during the Blitz, but you may be surprised what these guys can turn up.

I got a guy to do mine, he was a student who like many advertised and this gave him an income, sorry can't remember his name now.

Good luck with it.

They came to Ireland in March 1920. All were ex soldiers, mostly Scottish. The Welsh came home to the mines, the English to ship building and the mills. Unemployment was the highest in Scotland, and records show so was alcoholism. The records I got sent over was for a soldier who's WW1 medal trio I had and with it was his service records whilst serving in the force. I was unaware he was a Tan. The records recorded he faced several charges for drunkeness whilst on duty and two for fighting with other men on his patrol, there mustn't have been any Irish about that night !