During the medieval period ores were worked extensively by the Crown on the Bere Ferrers peninsula, between the Tamar and Tavy rivers south of Tavistock. Unlike contemporary activity in other non-ferrous mining fields, these were deep shaft mines working a rich but restricted resource. Unable to move to more accessible sources of ore, they utilized the best technological practice in drainage and smelting to maintain output.

There is a remarkable survival of the field evidence for mining technology from that period. Providing a unique physical link with advances in drainage techniques in the mid 15th century.

Silver bearing ores have been worked on the Bere Ferrers or Birland peninsula, between the Tamar and Tavy rivers south of Tavistock, for nearly six centuries. By the middle of the 19th century there were at least a dozen mines, some consolidated into larger setts. The majority of which worked silver-lead deposits found in north-south crosscourses.1 Two of those crosscourses, at South Hooe and Cleave , proved particularly rich whilst another to the east, north of Lopwell, was of only marginal economic importance. However, only the deposits on the crosscourse north from Cleave to Goldstreet were known to the medieval miner and worked extensively from 1292 to the end of the 15th century. By the early part of the 14th century there were four mines at work, South, Middle, Fershull and the Old Mine.

Working of silver-bearing ores in the medieval period was in the hands of the Crown which held the prerogative on all precious metals plus copper and tin. Initially the mines at Bere Ferrers were worked directly by the Crown but after 1350 they were granted on lease to outside interests, with the Crown retaining a royalty and right of pre-emption on the produce.

The miners themselves held none of the customary rights enjoyed by the tinners of Devon and Cornwall or lead miners on Mendip and elsewhere. If necessary they were pressed into service and worked under the direct control of Crown officers or the lessee. An initial lack of adequate local expertise in mining and smelting meant a workforce from areas as far as North Wales, the Derbyshire Peak, Mendip, the Forest of Dean, and Cornwall was assembled in south Devon, bringing with them techniques suited to less complex ore deposits. It was only with experimentation, particularly in smelting, that processes adequate to the silver bearing ores were developed.

Known workable deposits of silver-bearing ores were a limited resource and the Devon mines, at Bere Ferrers and Combe Martin, dominated 'English' production from the late 13th century until new mines were opened up in mid Wales in the late 16th century.2 Output peaked in the early years, 1297 and 1306, but even then only at a little over 23,000 ozs per annum. Average production was around a tenth of that figure. Nevertheless, the demand for silver was such that the mines remained at the forefront of technological advances throughout the medieval period.