Castor is explictly focusing on telling stories (she tells us in the preface), but as a champion of four often maligned queens she's inevitably revising the traditional historical approach. So when she considers defining moment of Matilda's near-reign, with King Stephen in prison and her preparing for her coronation, when her "arrogance", commonplace historiography tells us, cost her the throne. Castor's explanation by contrast is that:
"Matilda faced two pressing and intractable problems: her relationship with Hishop Henry, without whom she would have not have been recognised as 'lady of England,' but who expected as the price of his backing a degree of control over royal policy that no monarch could tolerate; and the attitude of Londoners, whose overwhelming economic interest in the trade route through Boulogne predisposed them to support Stephen's claim to the throne...but the moment Matilda tried to tackle those problems with what her father would have recognised as kingly authority, she was accused of acting with a headstrong arrogance unbecoming to her sex...."
She's critical of Margaret too, but also sympathetic to the impossible position of a queen having to try to guide an imbecilic king in the interests of an infant son:
"Loyal wives did not customarily supplant their husbands at the head of government. The implication was that unnatural impulses were at work, both inside and outside the royal bedchamber. Margaret might seek to associate herself with the virtuous queen of heaven in her attempt to rule through a royal trinity of king, queen and prince, but the evident fact that she was the prime mover of the three threatened to wreck the whole enterprise on the rocks of her aberrant behaviour as a wife and a woman."
So this is clearly a feminist history, not championing, unquestioning feminist history, but critical, considered feminist history - and recovers for us four women whose struggles deserve to be remembered, for all that they were extraordinarily unusual in being offered chances of power in a profoundly powerless age for women.