Villages By the Sea Series 5. 4 St Agnes Cornwall - https://www.bbc.co.uk/iplayer/episode/m0025grx/villages-by-the-sea-series-5-4-st-agnes

Ben Robinson investigates how a Cornish gem became world-famous for tin. In the bay, the archaeologist unravels the epic story behind the hundreds of huge carved stones that lie scattered in the surf. There's a look at some medieval technology in action at one of the oldest tin refineries in Britain, and a local doctor consults his ancestor’s 150-year-old medical diary for evidence of past ailments.