For Dr Williams, or more likely his successor, the unavoidable question has to be whether the received model of Anglican unity, based on an ecclesiology more Catholic than Protestant, is still realistic when many parts of the Anglican world are not prepared to play by its rules. There is no central Anglican authority, a situation that did not seem to matter when a general consensus existed as to what Anglicanism stood for. Its absence now makes the task of the Archbishop of Canterbury, titular head of the Communion and chief defender of its unity, uniquely burdensome. Other international Christian denominations, such as the Lutherans and the Methodists, have felt that the universal dimension of their faith was sufficiently expressed by a looser federal structure, without any attempt to impose uniformity of doctrine or church order. If that pattern is the one towards which Anglicanism is inexorably progressing, any attempt to head it off will be a wasted effort. With his experience, it would not be surprising if Dr Williams was beginning to think he has given it his best shot, but that the task may be beyond even human capability.