Take the Roman Britain coin, known as a radiate, found in Headbourne Worthy, Hampshire. "On the face of it, it looks a grotty old coin, which it is, I guess," said Lewis. But it helps tell the story of Carausius who declared himself emperor of Britain and northern Gaul between AD286-93, breaking away from the Roman empire. He was assassinated by his treasurer Allectus. The newly found coin is just one from an astonishing variety of nearly 4,000 which were struck during Carausius' reign. Other finds include a pure gold arm ring weighing 300g and dating from the eighth century...