Any ideas what the ratio of drift mines to deep mines is in the UK?

I think most of our disused mines (by area) are deep, and pretty dark places - don't even need to reach pit bottom for total blackness.

Having been down a mine few times not sure I'd want to farm down there!

Surely the real answer is to grow the same foods in commercial greenhouses, heated via geothermal heat pumps and if we're short of land to do this we can always use golf courses for farming!