Sorry busylizzie I misunderstood your post - I thought he was still alive. Your problem sound very similsr to mine.
I also had a problem with the name of one of my husband's great uncles - everyone said he was called Don......I looked for ages and couldn't find him, then the penny dropped when I found the rest of the family, he wasn't Donald or anything like that, he was Gordon. We don't all use the same abbreviations either!