Given the butchery and sexual intrigue of the immediate pre-Tudor era, it is surprising novelists and popular historians have not turned to the incestuous Plantagenets more often.

Philippa Gregory is busy rectifying this oversight in fiction with her White Queen series, recently televised on the BBC, which looks at the lives of Elizabeth Woodville, Margaret Beaufort, Anne Neville and Elizabeth of York. Now Alison Weir, who has already published histories of Elizabeth of York's brothers, the 'Princes in the Tower', as well as medieval queens Eleanor of Aquitaine and Isabella, wife of Edward II, is turning to this period. But how fruitful is it for historians?

Like the Tudors, it is dominated by colourful men: in place of Henry VIII, we have his grandfather, the equally glamorous but lustful and eventually obese man he seems to have so closely resembled, Edward IV, and his paranoid, controlling father, Henry VII.

But it is also full of women: the wives, sisters and mothers who populate the outer reaches of history, excluded from political decision-making but at the heart of the dynasty. Elizabeth of York was the first child of Edward IV and Elizabeth Woodville - her paternal grandfather was Richard Duke of York, the grandson of Henry V. Her husband, Henry VII, was the son of Margaret Beaufort, herself a great-grand-daughter of John of Gaunt, son of Edward III, and Edmund Tudor, son of Owen Tudor and Katherine of Valois, who had been married to Henry V. It is a complicated genealogy, which means just about everybody in Elizabeth's family tree has a claim to the throne - and in fact, Henry VII's was weaker than most. He needed to marry Elizabeth to help bolster his claim, after defeating Richard III at Bosworth.

But as Elizabeth left only some letters in her own hand, it is hard for historians to know what kind of woman she really was. The Queen of Hearts in a deck of playing cards is meant to be modelled on her image, and she was often depicted as selfless, beautiful, faithful to her husband, adoring of her children and siblings, good with money and charitable. Almost too good to be true, but such a favourable depiction was necessary - after all, she had married the man some even suspected of murdering her brothers, including the rightful heir to the throne.

Richard III was the main villain of the piece (and she had considered marrying him, too), but many found it odd - and said so - that Henry ordered no public commemoration of the boys. Was Elizabeth trying to secure a future for herself out of desperation, or ambition? Odder still was her acceptance of her husband's treatment of her mother, who was soon deprived of her lands and whisked off to a convent.

Did Elizabeth collude in the exclusion of her mother from court (although Weir asserts that Elizabeth Woodville did still attend on occasion)? And how did she really get on with her fearsome mother-in-law, Margaret Beaufort, who adored her only son?

Weir adheres to the conventional story without giving much weight to new theories, preferring instead to stick with the facts about daily life for a Plantagenet princess-turned-Tudor queen. We learn a great deal about what materials made up her clothes and for what occasions; what daily expenses were exacted on her 'privy purse'; that "it was a mark of rank to look clean and smell pleasant"; how the process of childbirth was carried out (herbal baths and a sitting or squatting position were favoured).

Elizabeth had seven children, of whom three died in infancy. The greatest tragedy of her life, after the murders of her brothers and the early death of her father and protector, was the unexpected death of her first-born, Arthur, the Prince of Wales, at the age of 16. His marriage to Katherine of Aragon would become crucial in the years ahead, when his younger brother and the only remaining male heir, Henry, married her as well.

Elizabeth's childhood was shrouded in secrecy and violence, hidden away in Westminster with her mother and sisters; her adulthood was a magnificent public relations job, giving nothing away. We can speculate all we like, Weir says, but historians cannot, and should not, even do that. It's for novelists to fill in the blanks.