The Stannary Prison on the Edge of the Moor
Lydford Castle is a deceptive structure — from the outside a squat, well-preserved square tower of late-twelfth century date, but set within an earthwork ringwork of Norman origin that predates the tower by a century or more. The ringwork was thrown up shortly after the Conquest, Lydford being one of the four Saxon boroughs of Devon and a place of strategic importance on the western approaches to the moor.
The stone tower was built in the twelfth or early thirteenth century and served as the administrative centre and prison for the Dartmoor stannaries — the tin-mining districts whose produce was assayed and taxed under Royal charter. Stannary law was notoriously harsh, and the castle gained a grim reputation: prisoners were kept in the ground-floor chamber under conditions that reportedly killed many before trial. The phrase "Lydford Law" — punish first, try later — entered the vernacular.
The tower stands to almost full height, unusually complete for a structure of its age. The earthwork ringwork surrounding it — the original Norman defensive circuit — remains clearly visible as a raised bank, making the site a rare survival of two distinct phases of medieval fortification in a single small area.