Val, At least in this case you do know where he originally came from, which is a huge plus. Odds are that you will find him buried in Hamburg or close by, although at least one ship containing returning internees was sunk. Certainly there ought to be parish records of his birth and probably other family members, which ultimately could lead you to more people and more clues and information. I have been amazed at how much the families still in Germany know about the ones who went to England a long time ago. This is not the easiest route, as it requires use of German records, possibly hiring a German genealogist, and probably a trip to Germany, but for someone who really wants to know what happened to him, there is some reasonable chance of success. This is assuming that you cannot get anything from the International Red Cross, which should be the first place to look.
If what you want is to know more about his experience at the Isle of Man, you could ask the people that maintain the library and site there if they have any records of him. Sometimes they do.
I will add him to my list, but am not actively doing anything with it at the moment. He does not appear on any of my other lists so far.
