1,700 years ago, a Roman commander declared himself emperor in Britain. Now a tiny silver coin found beneath a railway is bringing his forgotten empire back to life

Nearly 1,700 years ago, a Roman naval commander escaped execution, declared himself emperor and carved out a rival Roman empire in Britain that lasted seven years. To strengthen his rule, Carausius minted high-quality silver coins bearing his own portrait. Today, one of those rare coins has been unearthed during the East West Rail archaeological excavations in England.