DFC,
What if the 'private site' is just a back garden? If the owner isn't aviation minded, would they even know (or care) what a Danger Area is?
They would, however, probably be able to tell you about the strange black (and blue and green and multiple other colours) helicopters that fly in and around the area at all times of day and night!
So, in this case, it's probably not the best idea to call the 'operator'. Like tegwin has already suggested, the best idea is probably to call Shobden and see if they can tell him any more. If the Air/Ground people can't help (I'm pretty sure that Shobden doesn't have ATC) then a call to Tiger Helicopters (who are based on the field and obviously operate locally) might furnish the required details.