Tom Holland is the author of numerous historical works, including "The Shadow of the Sword," and is the presenter of the BBC's Making History.

Although Hilary Mantel is apparently yet to begin the third volume of her trilogy of novels about Thomas Cromwell, we can be confident of several plot twists that it will not feature. Cromwell will not precipitate a civil war. He will not betray the husband of his foster-sister, with whom he is in love. He will not escape the executioner's block. His downfall is scripted. The history books cannot be cheated. Mantel's Cromwell is as bound to the inevitability of his doom as any prisoner to a rack.

In the hands of a great writer, of course, the fact that we already know a character's fate can serve to heighten rather than diminish tension. For all that, though, the pleasure to be had in following a narrative and not knowing what will happen is a primal one. Next week sees the return to our television screens of a series that, like Mantel's two Tudor Booker prize winners, charts the pleasures and perils of political ambition. In a trailer for Game of Thrones, the voice of the actor Aiden Gillen can be heard defining chaos as a ladder: "The climb is all there is."...

Adding to the impossibility of deciding where Martin may be taking the fabulously complex strands of his plot is that the world of Westeros does not draw for its inspiration on a single period of history. Baelish may seem a figure conjured from Tudor mythography, but the king who rules in the first book in fact resembles Henry VIII less than he does his grandfather: the founder of the Yorkist dynasty, Edward IV. The back story of the series certainly derives from the wars of the roses. Just as the house of Lancaster was toppled by the house of York, so, at the beginning of Game of Thrones, has the ruling dynasty of the Targaryens been toppled by a usurper, Robert Baratheon....