You beat me to it!
Yes, worked in the late 1980s by workers displaced from Oakeley, then sold and 'vigorously' untopped in the 1990s. Now abandoned and flooded.
Slightly surprising it's not drained somehow, as it would have been a lot of hassle to continually pump it, but (a) untopping may have blocked the (drainage) adit; and (b) originally slate was uphauled, which suggests there may not have been a low adit.
Not having checked the OS map, I'd guess it's pretty flat around there?
Probably worth a visit on a winter's afternoon, if only to confirm that all the chambers are flooded. I have a supply of about 20 little dinghies somewhere...
Hello again darkness, my old friend...