I saw this on a non militaria related forum, discovered by someone working in the house. I will copy the narrative posted on that forum which accompanies the photo but I will stress no other information will be forthcoming as it is in a private residence and for obvious reasons it will not be disclosed.
Many thanks to the person whose permission was sought to post it here.
"I was working in a house in Leicestershire when I can across this painting of a hunter and his dog. The house was used to accommodate German POW's in the last war, and it seems one of the inmates painted this on the bare plaster wall. The wall was subsequently wood panelled, and so the painting has been covered until now. The room will soon be re-panelled, and so this image will be concealed again until who knows when. I just couldn't see it done without taking a photo. How amazing would it be if the artist was still alive and could see his work again after the passage of so many years!"