I'm going to bite...
Not much you can do if someone gets airborne in their own aircraft, flies in Class G airspace, doesn't talk to anyone (because they don't need to), calls up ATC without response (because it was closed) and then decides to land at RAF Valley anyway....
If someone steals an aircraft/hijacks/enters UK airspace without permission/a flightplan on the other hand.... it is passed on to the people who need to know.
If you don't know the details etc.