The PDCMG don't have a publicity officer and are noticebly shy nowadays, but there was an email to all clubs and people on the PDCMG mailing list, so implicitly left it to keyholder clubs to tell their people asking for access. I suppose anybody else asking for a key would be told at the time, which isn't unreasonable. Whether they actually asked 'the owner' for permission is another matter...
Doesn't surprise me as the final shaft looked as though it would need reinforcement sooner or later and it is getting on for 20 years since it was opened up.