One thing I'd like to add, since the site covers Merry Tom mine, is that on a recent visit with the WMRG we found that the locks had been cut off and replaced with bolts.
This is a bloody stupid action on the part of whoever's done it, Merry Tom is a major bat roost over winter and part of the access agreement is that no-one goes in between October and April so as not to disturb the sleepers. The locks have been replaced, but if this happens again, and there is disturbance to the bats then there is a real possibility that Natural England might require more permanent seals on the entrances. WMRG are quite amenable to allowing access over the summer and they're putting new plates on with up-to-date contact details so between that and this website, there's no excuses for breaking in.
Follow the horses, Johnny my laddie, follow the horses canny lad-oh!