Secrets of the deepest gypsum mine in the world

Available for over a year

Birkshead drift mine near Appleby-in-Westmorland is a 1000 ft deep under rolling farmland. There's little on the surface to give you a scale of the vast workings, which are reached by driving 5km down through tunnels large enough to take a Land Rover. Andrew Carter discovered a world apart, as deep as the Pennines are high, that supplies the raw materials to make plasterboard for the building industry.