Suggest you go to http://www.forces-war-records.co.uk/
where you will find service records of soldiers. They have George William for 1915 and 1916, and George W. for 1916. There is a cost so make sure you opt out of automatic subscription renewal.
You have probably been to the Commonwealth War Graves Commission website at http://www.cwgc.org/
and were unable to find a record of his death in the forces but his service record should indicate his regiment. You need to check the regimental diaries to see where he was most likely to have been in action when he died. Unfortunately in places like the Somme many died and were recorded on memorials as unknown soldiers. If you get a chance to tour the area where he was fighting you will probably find that there are several possible cemetry sites. It's an emotional experience and like me you will probably weep at the realisation of the magnitude of the carnage.
Wishing you well in your search.