I called in to have a look at it last week. Impressed with the size. Reminded me of Pink Floyd Live in Pompei!
https://vimeo.com/191521748
Would be ideal venue for concerts. Few neighbours. Car parking. Must check that they are cabling in power supply.
Perhaps the Bishop could use it for one of his revivalist meetings like John Wesley used Gwennap Pit (review here
http://www.shipoffools.com/mystery/2010/1865.html) which I visited last year?
'If no one went no faster than what I do there'd be a sight less trouble in this world'