In Richard Eyre’s rambunctious 17th-century romance “Stage Beauty,” we witness a moment in history when British theater evolved almost overnight, much as cinema did with the advent of sound.

Put another way, Shakespeare was a real drag until men stopped wearing dresses. Played with tarty self-assurance by Billy Crudup, Ned Kynaston is a shining star on the London stage in an era when women — by royal decree — are forbidden from acting. Filling the gender gap, pretty Ned enjoys fame as a “complete stage beauty,” playing Shakespearean heroines such as Othello’s Desdemona to the delight and frank infatuation of men and women alike.

Finding stardom in a dress did not come easily or naturally to Ned. Doted on by his adoring dresser Maria (Claire Danes), he ruefully recalls his harem days as a young boy, when his mentor eliminated "every masculine intonation" from his person over years of stage training.

But Ned is philosophical; he got a nice career out of the deal, and can bed down with whomever he pleases, whether it be the Duke of Buck (Ben Chaplin from "The Thin Red Line") or giggling socialites who want to “verify” his masculine credentials.

Ned’s salad days are about to wilt, however. With the Reformation in full swing — and the crown’s fun-hating Puritan usurpers all but swept away — England is in the mood for change. Eager to please his libertine mistress, King Charles (Rupert Everett) tears down the barriers to women in theater.

Suddenly, Ned — who thinks himself incapable of playing a male character — is out of a career. Adding insult to injury, Maria (a closet actress all this time) is the new darling of the London stage.

Director Eyre, a longtime theater director who made a cinematic splash with “Iris” three years ago, finds a compelling and singular hero in Ned (based on a real but obscure actor from the British stage tradition). Chauvinistic and insecure, Ned’s relationship to his craft is incestuous, revealed in the scene when he brattily fumes: “A woman playing a woman! Where’s the trick in that?”

As the adoring understudy who helps Ned discover his inner manhood, Danes gives a transparent, open-faced performance that nicely frames Crudup’s calculated aloofness. Jeffrey Hatcher’s smart, bawdy dialogue, adapted from his own stage play, gives the stars something spicy to chew on. With all due respect to the Yanks, Everett gives the film’s standout performance as the foppish, merrily amused King Charles.

Enshrined by the filmmakers as the midwife of modern British theater, he’s a man who respects the craft of acting, but knows that a wig and a dress does not an actress make.

‘Stage Beauty’
Starring: Billy Crudup, Claire Danes, Rupert Everett, Ben Chaplin
Rated: R (sexual content, profanity)
Running time: 110 minutes
Playing: Opens Friday at theatres Valleywide