Jane Seymour briefly slides through the pages, whey-faced, shy - or is she sly? She has been planted in Anne's household by the Seymour family (who have their own dark secret), partly as a hedging bet for future favours, partly as a spy; and "her eyes are the colour of water, where her thoughts slip past, like gilded fishes too small for hook or net."

This is history and character left properly complicated, unresolved. The protagonists each have their own versions of England's past, warped by family myth and prejudice, or dangerously rootless; and their knowledge of the affairs of the present is a tangled skein of salacious conjecture and malicious gossip. Who knows what the truth is about the relationship between Anne and the King? Cromwell, better informed than most, thinks he knows how they look at each other: "For a second he understands it. Then he doesn't."

Mantel is a thoroughly modern novelist; yet she is in many ways ideally suited to writing a historical novel. Her fiction is always skewed, genuinely strange, wittily out of kilter with the present-day world. The otherness of the past presents no difficulties for her: she neither strains to make it relevant, nor labours to show its distance from us: she is a novelist who knows what it is to feel foreign from herself. Wisely, she avoids any attempt to imitate Tudor English. Even authors who are exceptionally good at it, like Peter Ackroyd, run into difficulties, since the brilliance of their performance deflects attention onto the pastiche.

As for the issues of the time, Mantel conveys them with subtlety and sympathetic passion. She shows that the motives and loyalties of all sides are impure, complex. Those in favour of the King's divorce are not, or are not solely, men seeking to curry favour by humouring the lustful whims of an absolute ruler. All know the price that will be paid - in blood, shed by untold numbers of Englishmen, both in civil war and against foreign powers - if the King does not provide the stability offered by a legitimate male heir. The first Queen's barrenness will smite all the nation, with the force of a curse from God, which it was believed to be. Cromwell may be the hero; but Mantel balances him with an unforgettable portrait of Katherine of Aragon, for whom, as so often in Mantel's fiction, a missing child is the core of tragedy.