Almost exactly 400 years ago - 20 January 1607 - a 12ft-high wall of water devastated the counties of the Bristol Channel. The catastrophe altered the coastline for ever - yet it's been all but forgotten.
Scientists Ted Bryant and Simon Haslett team up to find archaeological evidence to support their belief that the event was not a freak storm but a tsunami.
Director/Producer Sam Roberts
Hadrian's Wall - Timewatch is on Friday at 9pm