It included a stone tower with a surrounding bailey, and rapidly became used as a prison and court to administer the laws in the Forest of Dartmoor and the Devon stannaries.

It was redesigned to resemble a motte and bailey castle, an antiquated design for the period but one that was heavily symbolic of authority and power.

[2] In 1068 William the Conqueror intervened in South-West England to put down widespread Anglo-Saxon revolts against Norman rule and set about pacifying the region.

[11] In the late 12th century Richard I's government attempted to promote the growth of Lydford, including revitalising trade in the town.

[13] This fortification is referred to in contemporary documents variously as a firme domus and castelli de Lideford, a "strong house" and "Lydford Castle" respectively.

[14] Archaeologist Andrew Saunders suggests that the new site was chosen because the earlier castle at Lydford was not owned by the Crown in 1195 and was, in any case, in disrepair.

[18] The south-east side of the bailey probably formed a small courtyard in front of the tower, in a space now occupied by part of the 13th century earthworks, and was probably the entrance to the original castle.

[23] The castle lacked the usual military features of the time, such as external gatehouses, and its design seems to have been intended to evoke the authority of a traditional defensive fortification rather than to resist an actual attack.

[24] Instead, as well as helping to deal with the wider problems in 1195, the castle appears to have been built with the intention of enforcing the stannary and forest law in Devon.

[26] The industry was regulated by the Crown, who taxed mining output and raised revenue from any fines imposed on those who broke the stannary laws.

[28] The output of tin increased from the end of the 12th century onwards, encouraging the Crown to extend its regulation and generate more revenue.

[29] In 1198, William of Wrotham, who controlled Lydford Castle at the start of John's reign, was appointed as the Warden of the Stannaries, a new office intended to provide additional rigour to the administration of the mining industry.

[40] Two more storeys were then built on top of the older walls, better executed with a higher proportion of granite stone and thinner, typically around 6-foot (1.8 m) thick.

[43] It is uncertain how many other towers or keeps have similar mounds, as excavation is usually required before the foundations can be examined, but Totnes and Farnham castles are known to have mottes build against the walls of the keep.

[45] It was instead probably intended as to superficially imitate older motte and bailey designs, with the completed castle echoing these former symbols of power and reinforcing the current political status of its owner.

[45] Richard's son, Edmund took over the earldom in 1278 but had little interest in Lydford, preferring Restormel and Lostwithiel; by his death in 1299 the castle had been left to decay and was in ruins.

[37] It reverted to the Crown, and when Edward II made his royal favourite, Piers Gaveston, the Earl of Cornwall in 1307, Lydford Castle was passed to him.

[37] Edward II and Gaveston fell from power in 1327 and Thomas le Ercedekne was temporarily entrusted with the castle and Dartmoor by the new regime.

[37][nb 3] Piers Gaveston's widow, Margaret de Clare, leased the property to Tavistock Abbey, and it continued to operate as a prison.

[47] It had a terrible reputation amongst Parliamentarians, who complained that it was used to summarily execute military prisoners and to extort money from innocent civilians, on fear of imprisonment.

[47] At the end of the civil war, the Lydford estate appears to have been sold off by Parliament [49] The castle was assessed by their surveyors to be "almost totally ruined" in 1650: the roof of the tower was still mostly intact, but the floors and their beams were collapsing, and the whole site, including the bailey, was only worth around £80.

[49] Repairs to the dilapidated building do not appear to have been carried out, however, and in 1704 a report was drawn up for the government, noting that the Stannary laws could not be enforced without a working prison.

[52] At the start of the 19th century, however, Sir Thomas Tyrwhitt, the Lord Warden of the Stannaries, began the construction of Dartmoor Prison at Princetown.

[57] By the 1870s, the town of Lydford was vastly reduced in importance from the medieval period and the castle's roofs and floors had either collapsed or been removed.