Thanks for your replies and the heads up on the permit, i'll get that sorted.
That document is actually what I needed clarity on. It mentions floor 15 is accessed by an adit (15b), but from the book, which I did manage to get from the Talyllyn, shows the adit being in a different part of the quarry on the other side of the valley from 10c which people seem to enter, and below 10c the map says 'site of adit 15c'....so i'm just wondering the following things. Is 15c accessible? If not, Does the adit 15b link up with 15c (I'm guessing probably not) and if not, is descending down from 10c or ascending up to 10c the only real option?
Thanks, Pete