Great theory, Dr Bill, but would you stop to take bearings when the sea is racing up the shallow sands at a speed of 30 - 40 mph ? (as I believe it does, round there.)
Rhub's right, of course. And there were other limiting issues as well - one is that there is a complete dearth of landmarks around those parts even during the day, and I believe this happened in the evening. Also, the royal party on shore wouldn't have had a clear view - it's dead flat. They may not even have realised what was happening until it was all over bar the shouting - and, no doubt, the summary executions. John was a typical Angevin king - short of everything, like height, temper and real intelligence. He did have a certain level of low cunning, however.
His older brother Richard was really no better. He just managed to do his worst direct damage in the Middle East rather than England. "Good King Richard", indeed! He bled England dry through taxes (which John had to collect, hence people's dislike of him) to pay for his crusading. And that ransom. And he would have been the first to string Robin Hood up on principle, if Robin Hood had really existed. Unless, of course, Robin was really attractive ...
