Pontius Navigator was correct in most of what he said. I believe it can be quite difficult to actually
prove that a pilot may have endangered himself, aircraft or passengers by flying into an active Danger Area and therefore get a successful prosecution under the Air Navigation Order. I'm certain that Salisbury Ops, the controlling authority for the Salisbury Plain Danger Areas had some success in pursuing prosecutions of pilots for tresspass, under the Military Lands act of 1892. Interesting when you think that the areas are sometimes active up to 35000 feet.
