A spot of history – the mineral rights to the area were owned by the Duke of Devonshire, and to develop the mine he brought in the famous Cornish mining engineer John Taylor which would doubtless explain the Cornish style design. The engine house is thought to date from about 1840, and housed a beam engine that was used for pumping water from one of the shafts, and it also hauled wagons of ore up a 1 in 4 inclined plane.
The area had already been mined for hundreds of years, but with the industrial revolutions increased demand for resources, improved facilities were required. Miners moved to the area from afar afield as Cornwall and Wales.
Production averaged 470 tons a year until the ore was exhausted, and the mine ceased operations in 1881.
Quite how it survived in an abandoned state for so long is a mystery, but it was subject to some conservation / restoration work in the 1970’s (although I don’t know what state it was in beforehand).