Johan, as a child I lived in a place called Redcar on the North east Coast of England . It was near Redcar that UB-110 was sunk. There was wreckage on the end of the rocks, possibly a mile from shore, that was reputed to be "a WW1 german submarine". My Father always told me that it was used for target practice during WW2. I only remember seeing a couple of mast like structures at low tide. I have read in other places that UB110 was retrieved by the RN, and then sunk. Whether or not this story was true or not, I can't really say, but I know that local folklore related to the fact of a submarine wreck off Redcar. Given that UB110 was sunk off Hartlepool, I have always assumed that this wreck was UB110. I have also heard comments on wreck diving sites that a WW1 german U-Boat had been "found" off Redcar. Hope this helps.
Stuart