The story of King Arthur and the quest for the Holy Grail is well known; less so is that of the coming of Christianity to Britain at around the time of the Roman invasion. It is generally assumed that both these legends revolve around town of Glastonbury, yet the paucity of evidence for this assumption has always been troubling to those who like their history to be founded on fact. In this extraordinary book, Adrian Gilbert reveals the location to be not just of the true 'Avalon' or 'Glastonbury' but of many other sites crucial to the Arthurian legend. 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.