Gerald of Wales and the Prophet Merlin

My subject is the remarkable role of the prophet Merlin in English politics from Henry II through to King John, as evidenced by the writer who outlived them both, Gerald of Wales. Gerald was born in 1146, just a few years after the publication of Geoffrey of Monmouth's History of the Kings of Britain; he died in 1223, after a long retirement from a busy but ultimately disappointing life: he had been a student and master in Paris, a courtier and diplomat in the service of Henry II and his successor Richard, an archdeacon of Brecon, but his dream of becoming a distinguished bishop had come to nothing. Despite all his business, he was an extremely prolific writer. Below is an approximate chronology of Gerald's works that are relevant to my argument (he in fact wrote much more).