I guess that if they are clearly displayed, the stewards can probably look a few cars down the queue to see if you have a sticker, and you wouldn't even notice that they have checked.
well... as per my OP...
ours wasnt in place on arrival and never actually got stuck on all weekend.
so nobody was checking on the ay in to field 4 or when we were on it (or at least our part I suppose but thats a bir random! LOL)
didds