In the 1990 edition of the TS Journal there is a 20 page article entitled "The History of Underground Photography in Cornwall".
I don't have a copy of that particular issue but if anyone is interested I can photocopy it the next time I'm in the CSC. Only problem is they have had the journal properly bound (good idea) in sets of three years which makes copying slightly awkward as you may have already noticed.
The past is a foreign country: they do things differently there.