I will be in North Wales between 11th and 16th of
May with "Hamster" who is also a member of this site and would be very interested in a trip to look at Rhosydd in more detail. Have been a little way in via the no.9 adit a couple of years ago, but were daunted at going too far as we didn't know the place (I have since tracked down a copy of the book)
Are you hoping to look at the lost eastern workings by any chance?
'I wonder how many breakfasts, and other meals we have missed inside that nasty clockless, timeless hole?'
'The Hobbit'
J R R Tolkien.