I've seen photos from Sharron Schwartz and some of her gang in there, looks quite interesting actually.
It would be a shame to have the access blocked off, a gate would be better. hey gated Gravel Hill but I think that is on the MOD end of the beach.
Perranporth beach is actually quite full of little traps like this though.
It seems that tourists treat the place like a big swimming pool rather than the dangerous place it really is. Whenever I'm down there I usually park up in the Droskyn car park and overlook the beach, when I'm sat there looking over it I am seeing people being dragged out left right and centre by the lifeguards, some people just don't treat the sea with the respect and caution that it deserves.
Parents need to keep an eye on their kids to a certain extent but the dangers of mine adits are very un-publicised on Cornish beaches, as a kid I had no idea what they were, they just looked like caves and the same could have happened to any child, they need to at least put up a warning plaque on the cliff next to the portals. But the again... that might encourage the more adventurous people to go in...
That shaft on Droskyn head is an accident waiting to happen though, there is no fence around it and a nasty little earth bridge going accross to it. You can look up into that shaft from below on the beach, so I wouldn't really care if the council were to just get rid of that earth bridge leading to it and stop people from risking looking at it.