Early on in Peter Flannery's roaring Civil War drama, The Devil's Whore, the aristocratic heroine falls in with the Levellers, political radicals from Oliver Cromwell's New Model Army. Angelica Fanshawe is feisty, as heroines in British TV invariably are, and her journey towards "the Left" of the 1640s sees her overcome dangers that would have destroyed a lesser woman.

Her Catholic mother abandons her as a child. She becomes a lady-in-waiting at the court of Charles I, but displays her rebellious streak by talking back to the king and her vapid husband. When war comes, Harry Fanshawe proves his weakness by refusing to stand his ground against the parliamentary forces. Charles executes him for cowardice, and turfs Angelica out of his court. Seeing her starving and defenceless on the street, a corn merchant invites her to dinner, then tries to rape her.

Flannery leaves us in no doubt that her assailant is one of the rising bourgeoisie who want to dominate England when Parliament prevails. This lusty bourgeois' rise stops, however, when Angelica saves her honour by stabbing him in the throat with a cheese knife.

She flees and finds John Lilburne, the great radical pamphleteer, whom Parliament imprisoned for demanding that the English revolution should benefit all freeborn Englishmen, not only the merchants. In his cell, Angelica reads Lilburne's manifesto. The corrupt Parliament must be dissolved, she recites, and a new one elected by "all men of good faith and not just those with property". Lilburne looks a tad embarrassed by the gender exclusiveness of his demands. Like a modern politician who has heard himself saying "he" when he should have said "he or she", he interrupts hastily to show Angelica he is no sexist. "The levelling of women cannot begin until this has been accomplished," he reassures her.

I do not wish to jeer. The Devil's Whore is the best historical drama in years. The acting is terrific - Andrea Riseborough's performance as Angelica will surely make her a star - and Flannery's script is gripping. Yet its portrayal of 17th-century radicalism is tendentious and anachronistic, for a reason that says much about the denials of our times.