Recently there was long thread about the BCA. I can now post possible answers to some of the questions, such as "Why is the BCA still raising membership prices when there is a significant amount still left in its coffers?"
Yes, a very interesting place. They open it for cavers from time to time. Some bits are rigged to make them more 'interesting' - like the leaking water pipe.
The rally on the basillica is amazing, I've done it twice with York Uni CPC. It's usually every 3 years but last time they only waited for 2. It takes a whole year to plan and 3 weeks to rig with over 3 k of rope. Its really brilliant everyone should do it.