In reply to Little Rascal:
I'm not aware of anyone who has tried to gain the Dervish slab since the big rockfall and the council who own the site still have signs in place prohibiting access, as well as some new fencing. Since the big rockfall, there had been a subsequent rockfall affecting and essentially destroying the route Gin Palace, which is right next to the Dervish slab.
I think any climbing activity here during the normally busy times at the country park would lead to the wardens being informed and then probably they would be compelled to ask those climbers to leave.
The "sole use" of the diving site only refers to the lower, car park level of the quarry, and is only enforced when the diving site is operating.
Elfyn Jones
BMC Access & Conservation Officer (Wales)