U Boot POW records

[Flying10uk]

Eden camp near York, Yorkshire, England is a very interesting place to visit and was an Italian, then German POW camp during WW2. Many of the original huts are still on site and form part of the privately run Museum that is normally open to the public. It is currently closed because of the virus. Obviously I don't know if your relative was held in this particular camp but it would have likely been a similar camp to this.

Award Winning Visitor Attraction, Malton, North Yorkshire - Eden Camp

Some interrogation reports, like some other material, may not necessarily have been declassified yet because 100 years hasn't passed yet since they were made. Some things are still secret from WW2 with the relevant files not yet having been made public.