In this extraordinary book, Adrian Gilbert reveals the location of not just the true 'Avalon' or 'Glastonbury' but of many other sites crucial to the legend of the Holy Grail and King Arthur. He shows how the core teachings of Christianity were kept secret by a dynasty of Welsh kings and saints and later (after the Norman invasions) by their surviving descendants. For centuries this remnant of the Brittano-Welsh nobility, still living in 'Avalon', kept alive a hope: they prayed that one day a new Arthur, one with the holy blood of the family of Mary flowing in his veins, would sit once more on the throne of Britain.Extraordinary as it may seem, this hope may soon be realised – for through the late Diana, Princess of Wales, our own Prince William, whose middle name is indeed Arthur, is so descended.