Worth noting that the BCA insurance also helps in arranging and maintaining access - at least we've found this here in Derbyshire. Landowners worry (or at least, their solicitors tell them they should worry) about being sued if an accident happens in a cave on their land, so if the regional council is able to reassure them by providing a BCA Insurance Landowner Certificate, that makes it more likely that the landowner will agree to access. This will work even if the cavers on their land are not, themselves, covered under the BCA scheme - though it obviously helps if cavers are able to produce their own BCA insurance membership card as well and some landowners do insist on this as a condition of entry.
In fact, under current law, the landowner is not liable if the person having the accident has freely and of their own volition decided to take part in what may be called "a dangerous activity", even on private land. However, there can still be a "try-on" (as per the Scout in the accident at Gaping Gill a few years ago) but at least if there is, the landowner knows that the cost of defending such an action will not fall on him.