Starting with William Blake's lost painting "The Ancient Britons”, this book shows how the visionary artist and poet reworked the Matter of Britain - the corpus of legends presenting an alternative history of Britain - into his own mythology. He thus adds to a tradition of Arthurian epic begun by Layamon in the 13th century and continued by Edmund Spenser in the 16th, in which a Romano-Celtic warlord becomes an icon of the English imagination.