Postscript: I saw the lad again at Fiveways this morning, he was waiting at the front of the queue and was a little more circumspect as he took the junction this time. Looking at the scenario of his prang yesterday I think it was the sharp camber change dropping the road surface away from him as he turned with a shade too much enthusiasm that was his undoing, I recall he lost the front very early in the manoeuvre. Still, he's back out there, if a shade more cautiously than before...