Britain At Low Tide

8PM, CH4

For her fourth adventure, the engaging palaeobiologist Tori Herridge explores the maritime, industrial and natural histories that are revealed when the tide goes out at the Severn estuary, on the border between Wales and England. On a bleak island, she investigates a mysterious medieval ruin to see if she can uncover the key to its past – who built it, and why? Was it a religious site, or perhaps it was an early lighthouse or beacon? Further along the coast, she visits the site of a medieval village that was simply swallowed up by the sea.