School of Rock: The Musical, New London Theatre

When's the last time you heard an Andrew Lloyd Webber musical described as a gas, a hoot, an unpretentious delight?

All those qualities, and more, are there for the savouring in School of Rock, which has reached the West End a year on from its Broadway debut and is going to make a lot of children (and their parents) happy for some time to come. And I don't just mean the wildly talented tykes who are in the cast. 

Lloyd Webber has always contained within him the would-be rock god, as evidenced across a diverse output that ranges from Jesus Christ Superstar (whose summer revival in Regent's Park won two Evening Standard Theatre Awards on Sunday) to the lesser-known, and lamentable, Whistle Down the Wind. His latest abandons all Pucciniesque aspirations to suggest a marriage between, say, Rock of Ages and Dead Poets Society, and its unabashedly sentimental conclusion comes preceded by that rare feel-good entertainment that genuinely does leave a smile on your face: Mamma Mia!, move over. 

Based, of course, on the 2003 Jack Black/Richard Linklater film, the narrative is as old as the hills, telling the time-honoured story of a galvanic teacher who changes his students' lives and, in so doing, is himself changed along the way. The difference here is that Dewey Finn (David Fynn, inheriting Black's screen role) is an unreconstructed slob of the first order, who grabs at the chance to fill in as a supply teacher at a posh American prep school simply because he needs cash to pay the rent. Not only does Dewey, passing himself off as his wonderfully-named friend Ned Schneebly, soon discover that the young charges in his care can rock out and riff with the best of 'em but he unleashes the Stevie Nicks-worshipping soul beneath the prim exterior of Horace Green headmistress Rosalie Mullins, whom the delicious Florence Andrews (pictured above) invests with the winning sense of a bad girl just waiting to break free. (She'd make a terrific Sarah Brown in Guys and Dolls.)

Along the way, Lloyd Webber and his highly unlikely book writer - none other than Julian Fellowes, of Downtown Abbey fame - get to poke fun at their own CVs: both Cats and Mary Poppins get referenced, the former a onetime tenant of this same playhouse. A passing swipe at the kids as so many "singing Oompa Loompas" is there to remind one of that other kid-friendly show playing several streets away.

But the beating heart of director Laurence Connor's always-buoyant staging are the children and Dewey's unfolding relationship with them, and there was no single sight more affecting on press night than watching those kids not on stage for that particular performance cheering their castmates and singing along from seats near the lip of the stage. Whereas the ongoing Broadway run has one set of child performers (plus covers), Equity regulations here require a rotating roster of three. At the risk of offending by omission, I can only say of the opening night line-up that no praise is too high for Amma Ris as the tight-lipped, indrawn Tomika who turns out - 'natch - to be hiding a voice worthy of Motown the Musical, and Logan Walmsley as the beaming-faced, Vogue-reading Billy, whose name check of Barbra Streisand is itself worth the price of admission. 

Fynn (pictured above right), for his part, may not have the voice to suggest he's waiting to join Genesis, and he doesn't suggest the abiding mischief that Black brought to the film and that Broadway lead Alex Brightman hints at in New York. But where this somewhat more innocent Dewey heartily delivers is in comic timing that lands a huge laugh on the topic of E=mc2. Lloyd Webber's score, with lyrics from his Love Never Dies collaborator Glenn Slater, asks a lot of its star performer, as one might expect from the composer of the larynx-shredding, throughsung Evita (still his best score). The challenge is there from the early "I Want" number about climbing to the top of "Mount Rock" or the determinedly catchy, much-reprised "Stick It to the Man", a paean to rebellion that might not be the first thing you expect from a member of the House of Lords. You have to wonder, too, given the ending quite why it is that Dewey et al are brought back for an encore. 

But this is showbiz, not real life, which is why an ambiguously intended line about Dewey touching the students can bring down the house without sending out a call for social services. School of Rock never tells us, by the way, what happens when the ailing Miss Dunham, the teacher for whom Dewey is subbing, returns from her sick-bed. One assumes in light of the transformations wrought at Horace Green that she is learning to channel Freddie Mercury or has, at the very least, taken up the acoustic guitar.

• School of Rock at the New London Theatre to 12 February 2017
• Read more theatre reviews on theartsdesk
• theartsdesk recommends the best musicals in London

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Cats. The danciest British musical ever is back

Evita. Operatic revival lacks satirical bite, but is elevated by a star turn

Jesus Christ Superstar. A classic musical reborn for a contemporary audience

Love Never Dies. The bad and the beautiful do battle in Phantom sequel

Sunset Boulevard. Glenn Close and ENO company do much to fill Lloyd Webber's half-empty vessel

The Beautiful Game. Spirited revival of football musical set in the Troubles

The Phantom of the Opera. Does the most successful entertainment event of all time still have it?

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