LONDON: The theater thrives uniquely on transformation, the process whereby we are nightly urged to give ourselves over to a character's age, temperament, girth, sometimes even gender when what we see in front of us would sometimes suggest the exact opposite of what we are being led to believe. Judi Dench, for instance, famously balked at playing that Shakespeare glamour puss, Cleopatra, claiming by way of mirthful response that she was a "menopausal dwarf " when the director Peter Hall cast her in "Antony and Cleopatra" now 20 years ago. In fact, the performance remains one of Dame Judi's greatest, a triumph of instinct, wit, and the sort of sheer theatrical alchemy on which Dench, now in her 70s, has staked her formidable career.

And so to back-to-back London openings that make a feature of transformation - and sometimes even headlines. According to press reports immediately prior to its opening night, fans of the West End musical theater star Michael Ball were supposedly disgruntled during previews of the show "Hairspray" to arrive at the Shaftesbury Theatre only to find that Ball wasn't appearing at that performance. The truth, of course, is that Ball was indeed there, giving his all in the guise of the Baltimore laundress and mother, Edna Turnblad, played in the recent film version by John Travolta. So successful had Ball's makeover been that his own adoring public thought he'd been replaced, even if the entire story has about it the whiff of good old-fashioned press agentry engendered to stir up interest. (Exactly the same complaints surfaced several seasons ago when first Michael Crawford, and then Ball, donned far more capacious padding to play Fosco in the London premiere of the Andrew Lloyd Webber musical, "The Woman In White.")

Whether apocryphal or not, the anecdote attests to Ball's singular achievement in a production from the Broadway director Jack O'Brien that speaks to virtues that extend way beyond the leading man (or should that be, leading lady)? Having reached the West End more than five years after this buoyant take on the cult John Waters film first opened on Broadway, a peppy, often deliciously pointed musical has lost none of its heart in the travel across the Atlantic. If anything, "Hairspray" is even more of a tonic here than it was in New York, given a British staging that doesn't try as aggressively to sell itself in that faintly wearisome, time-honored Broadway way. The result is that the day-glo colors of David Rockwell's sets - the stage itself is an hymn to aerosol - and William Ivey Long's costumes shine just as brightly, while allowing actual truth to peek out from beneath the potpourri of hairstyles that the show's title and its period (the early 1960s) demand.

Most theatergoers by now probably have some foreknowledge of the story, which tells of a chunkily built white teenager, Tracy, whose ability to groove rocks a racially segregated city itself in thrall to the gathering enthusiasms of rock 'n' roll. While the Marc Shaiman/Scott Wittman score at once pastiches and encapsulates an era, Tracy comes to embody an integrative force far larger than even her considerable frame. As the title of the closing number puts it, "you can't stop the beat." Nor, happily, can one stop the most sensational professional debut I have seen in years, in this case from the 22-year-old Englishwoman Leanne Jones as the ebullient Tracy: a take-no-prisoners kind of gal even when Mark O'Donnell and Thomas Meehan's book lands much of the cast in prison, which in turn allows for a neat, quick nod to the ongoing musical revival of "Chicago."

Her acting as rich as her voice is resonant, Jones anchors a British company that, in addition to the baby-faced, saggy-armed Ball, includes standout contributions from Tracie Bennett as the resident baddie, Velma Von Tussle, and Rachael Wooding and Elinor Collett as pubescent flip sides of the impulse toward a generosity of spirit in a production besieged by transformation that may well leave you transformed.

It's been nearly 30 years since I first saw Caryl Churchill's play "Cloud Nine" Off Broadway in a theater in Greenwich Village, an area whose streets seemed to thrum with the same liberating impulses that are so acutely anatomized in Churchill's career-making play. Each time I've seen "Cloud Nine" since, I remain impressed by the level of formal invention to a script from a dramatist who surpasses even Harold Pinter and Tom Stoppard when it comes to literary experimentation...