In this episode Derek and Lawrence tell the story of the ‘Mortar Wreck’, the oldest shipwreck ever discovered off the English coast. Over a period of three years, the intrepid duo have gone to sea to observe diving on the medieval wreck, and witnessed beautiful carved marble artefacts come to the surface after 800 years on the sea floor. Having followed these finds through the conservation process, the show culminates in the launch of a fabulous new shipwreck gallery at Poole Museum in Dorset, where Derek and Lawrence come face to face not only with artefacts from the Mortar Wreck but also a 2000 year old log boat, carved wooden heads and even a submerged euphonium.