There is an abandoned lead mine near Sheffield, just outside a village called Castleton. The village is famous for the craftsmen who make jewellery from the local stone Blue John, which can only be found in this specific area. The mine is called Speedwell Cavern and we travelled underground through this mine on a man-made canal, in a small boat, guided by a comedian called Alex. It was a unique way to spend an hour, learning about a bygone era, child slave labour, economic hardship and the greed of the ruling classes. It’s well worth a detour for a visit.