Er..
Anyone care to tell me which mine in North Wales had 44 floors or a vertical extent of 2,640ft?
Unless Britannia had some hidden extension down below sea level, I’m stumped.
I can get Oakeley to a smidge more than two dozen floors. Any takers for more? :o
Well, there were not many. Oakeley must have been close to that in places, given that G floor exceeds 1300 feet and the floors go down as far as S. That's 12 further floors and at 50 feet spacing that would add 600 feet, so 2100 feet underground. But that's only a rough guess without looking at surveys. Might possibly have exceeded that.
As for Metal Mines - err, I cannot say for sure but I bet some of the Halkyn Mountain workings were that sort of money. The Milwr tunnel itself was about 1000' below grass around PYB shaft, and the workings I believe extended significantly below that horizon. 1600 feet below? Possibly not. But I don't know.
The only other mines in North Wales that deep were the Collieries around Wrexham. I believe the lower seams worked at Gresford were more than 3000 feet down, and I expect at Llay Main too. They were extremely deep collieries.
None of the above will help our friends though! They won't be going anywhere anything like 1/2 a mile deep in North Wales, but as your good lady pointed out, that could be horizontal. But if it's a low-to-high challenge, it would be a bit rubbish if it wasn't somewhere "deep".
The only other place I can think of is Electric Mountain, which is close to them. It's not a slate mine, although it's under a slate quarry, and it's certainly deep. But I'd be amazed if that's the place, the security there is understandably very tight and I just can't see them agreeing to that. Besides, it's peddled as a "mine trip".
Best of luck to them! But the "we're not saying where we are going, but please bring your own headlight" text on their advert doesn't inspire much confidence with me. Maybe I'm just a bit cynical these days.
Beneath my steely exterior beats the heart of a dashing hero