In reply to wilde: Hmmmm, having climbed there I think that the woman may be irritated by two probably separate things.
a) Climbers (ok) coming up on the other side of her fence (whether she owns it or not).
b) Yobs. I have been affected by yobs around that area. They can be noisy and looking for trouble. On one occasion, yobs were lobbing sticks etc at me whilst I was belaying my mate at a crux.
Just to mention, it is my understanding that the Police probably wouldn't get involved if you are not causing any nuisance as isn't trespass a civil and not criminal offence? Theoretically, the woman would have to sue you for damages if she indeed did own the property.
Hmmmm, she obviously seems disturbed. Under those circumstances, is it not possible to engage the woman on a friendly basis to understand her perspective a bit more and possibly try to allay her fears?
Next time, I go climbing there, I'll try a friendly approach and see what happens but perhaps you might be right a friendly visit from the BMC might be in order?