Hi Paul,
this is an old post I am responding to so not sure you are still out there..... My partners father was a German POW at Arbury Hall. We have managed to find a lot of information about him from the German military records and the Red Cross. We visited Arbury Hall in September last year and have photo's of the engravings the POWs made on a bridge there. Get in touch if you are interested in sharing info.
Regards,
Maz