Legally Blonde, Savoy Theatre

Audiences genuinely love Legally Blonde, and all but the most churlish of critics should crack plenty a smile, as well.

A feel-good show that - unusually, in my experience - actually does leave you on a high, this stage adaptation of the 2001 Reese Witherspoon film benefits immeasurably from a rapturous star performance from Sheridan Smith as the unlikely heroine of Harvard Law School, Elle Woods. Throw in two terrific supporting turns from Alex Gaumond and Jill Halfpenny and a production that pushes for effect considerably less than it did on Broadway and you've got a bubblegum musical that shines even more brightly than Smith's blonde wig. Sondheim it ain't, to be sure, but Legally Blonde is seriously fun.

I grinned quite a bit when I saw director/choreographer Jerry Mitchell's 2007 Broadway version of the same film, which starred New York Hairspray alumna Laura Bell Bundy as the determined ditz who discovers that brains can in fact co-exist with getting a boyfriend and a passion for perfume. But as happened similarly to Hairspray (which Mitchell choreographed but did not direct) in its trans-Atlantic crossing, something about the ecology of the West End allows Broadway slickness to subside in favour of a softer, sweeter touch.

This is a confection that could turn mechanical in lesser hands in the creators' self-evident desire for a stage franchise, so it's impossible to praise too highly the leavening spirit of leading lady Smith in her breakout musical theatre performance to date. Here at last is the centre-stage dazzle attempted though not quite achieved by Sweet Charity, whose principal character, as it happens, isn't that dissimilarly lovesick. But whereas Tamzin Outhwaite's Charity Hope Valentine cracks a grin that shuts the playgoer out, Smith's Elle embodies pluckiness attired in pink and delivered with very real heart. I've seen my share of robotic standing ovations over the years; by contrast, the depth of feeling that greets Smith's curtain call is as affectionate and honest as the performance itself.

The narrative arc is preordained in a hymn to girl power that lands Legally Blonde in the same emotional terrain as, say, Wicked and Mamma Mia!, Elle's occasional Greek chorus a younger version of the chums who exist to prop up the spandex-wearing Donna in the ABBA songfest. And as is the way of such fables, Legally Blonde basically requires the audience to figure out the outcome well before any of the people on stage do. A first glimpse of Gaumond's slightly geeky, supremely charming Harvard habitué, Emmett, and we can see at once that Elle should be making tracks for him and not for the vainglorious Warner, whom she has crossed America to try to conquer.

It helps that Canadian performer Gaumond - his nationality evident from an occasional "anyhoo" - scoops up every scene he is in, leaving Duncan James's quavery-voiced Warner looking faintly waxen from the sidelines. (On the other hand, that's not entirely out of keeping with the character, who exists to be disposed of.) The plot otherwise doesn't benefit from undue scrutiny, a sassy manicurist, Paulette (Jill Halfpenny, in fighting trim and very funny, indeed), on hand simply so we can compare and contrast two separate romantic quests. Paulette's affections are directed toward a delivery man with a Chippendales physique - Chris Ellis-Stanton has the role down to a finely buffed T - while Aoife Mulholland's exposed midriff does its considerable bit to keep more red-blooded patrons entertained. (Mulholland plays the fitness fanatic at the centre of the murder trial that makes Elle's reputation as a proper legal mind.)

Representing the older generation is Peter Davison as a professorial perv whose big first-act number ("Blood in the Water") allows the tireless Smith a brief moment of rest, and there are five dogs that alternate as the show's two scene-stealing pooches. I saw Bruiser and Monty, and full marks to both.

One can anticipate the cavils Legally Blonde has faced already in America and will continue to confront here. Mitchell's dance steps more often than not devolve into calisthenics, though some of that comes with the script, and the score by Laurence O'Keefe and Nell Benjamin is bouncy and upbeat in a poptastic way that makes for great MTV without announcing itself as a musical theatre keeper in the way that the music for Hairspray, say, already is. Heather Hach's book (slightly tweaked for the West End) is shameless about cribbing not only its MGM source, as is to be expected, but cultural references ranging from Simon Cowell and Oprah to Sex and the City, with the opportunity for a Riverdance pastiche thrown in: Paulette, you see, has a thing about Ireland.

And yet, as the first major West End opening of 2010, the show sells a welcome song-and-dance sizzle with a professionalism coupled with charm lacking in both of last year's large-scale musical contenders, Sister Act and Priscilla. And for as long as Smith stays with it, theatregoers surely will, as well. "Everyone has their secrets," Elle admits at one point. "For years, I denied my highlights." Well, it's time to let this secret out: the girl is a bona fide star.