With luck your local library will have a copy of Who Was Who covering the relevant years. People listed in Who's Who were migrated to Who Was Who after their death.
Worth trying to get hold of The Times Archive, again with luck through your local library, and searching to see if you can find an obituary.
As Stan notes, he's also in the DNB, which again you'll be able to get to via your library. He was quite some man, the biography is impressive. The DNB gives some leads to finding his papers in some archives.