Graham, I find your argumet illogical. If a landowner is happy to allow a surface dig, then it surely can be assumed that he or she would be prepared to allow cavers to visit the cave which lies behind the dig, if found to exist. I am not arguing for a generalised right to carry heavy equipment and possibly explosives across private land and tip spoil away when generated. I am arguing that unless there are pressing reasons (and the roadworks at Carno may constitute such reasons, and BTW of course I know that the cave lies down a long adit), then there should be a general, legal presumption that cavers should be allowed to go down caves, just as walkers can walk up hills.
I realise it may take us a long time to get to that point. But it seems to me that our sport is getting ever more restricted, especially in Wales, for reasons which are, to put it mildly, questionable. I think it's time we started a debate about what we are going to do about this. And in case anyone hasn't noticed, very few cave entrances are on housing estates. Arguing about the general principle from a single very unusual and isolated case doesn't make sense to me.
I also think some of the restrictions which exist on caves which are partially open need revisiting. For example, why can't anyone under the age of 16 go down caves such as Agen Allwedd, Longwood and GB? I like taking my kids caving and they're pretty responsible. I like to think I am. It's amazing how many places they're not allowed to visit. (My older son will be 14 this year and is very competent.)