Have you checked out the commonwealth war graves commission web site as they have litings of almost everyone killied in the wars with their rank, no. and sometimes parents, wife's name where died and when which war grave and which panel no etc. You've probably already sussed this out also another thing to try is to e-mail the town hall of the appropriate place and ask them to help you some are ever so helpful..
When I was researching a member of my family whom I was told died on HMS
Ajax I e-mailed the town of
Ajax in Canada as it was named after the ship and its street names were named after the men on board, they sent me out town maps and various other information even though when it came down to it he hadn't been on board when it sank...eitherway the information was fascinating. If you get on the web you can find out almost anything just type in the main keywords and see what comes up in the search bar...
Good luck