Earlier this year, Helen Mark visited the Isle of Eels in the heart of the Cambridgeshire Fens for its annual eel day festival. She joins the parade of eels through the streets and takes part in the World Eel Throwing Competition (which thankfully involves no real eels). She also learns about the life cycle of the eel and discovers how this extraordinary fish is intimately bound up with the history and culture of Ely. Producer Sarah Blunt.