Often, people like to wait until an event appears on the 100 Marathon club list before entering. It gives added reassurance that, if you’re counting these sorts of things, completing a marathon distance at Marabank will count as a trail marathon for the 100 club, and completing an ultra distance within the seven hour cut off will count as a trail ultra.
Of course, if you only want to do one lap, you still get to go home with a medal and the pleasure of having spent some time in pleasant company and beautiful surroundings.