When clubs join BCA they are asked, among other things, where their main caving interests/areas are and these used to be recorded on the list of BCA clubs and sent out each year to regional secretaries so they could check that their member clubs were paid-up members of BCA. (Some regions require that their clubs are paid-up members of BCA before they are allowed to join.) The list didn't include any details about the club or any contact details for it, just the name and the regions where they said their caving interests were.
It always puzzled me, when I was Secretary of DCA, that I'd come across clubs on the list who claimed to be mainly interested in Derbyshire but they'd never approached DCA for membership and, before the days of websites, etc. they wouldn't have been sent any information from DCA. Occasionally, if they seemed to be a newly formed club, I'd ask Wendy for their details so I could contact them and ask if they'd like to join DCA - and very often the answer was yes, but they hadn't known about regional councils, and they were quite pleased to join DCA as it cost them nothing if they were members of BCA.
Does CSCC's constitution still say something on the lines of "... a club becomes a member by expressing a wish to do so ..."? I seem to recall it did say something like that once.