The 2017 cast of Matilda
The 2017 cast of Matilda
© Manuel Harlan

After its cascade of rave reviews in Stratford-upon-Avon last December, I was expecting to really enjoy the RSC's musical version of Roald Dahl's brilliant children's story. And I did.

But there are a few bumps in the adaptation by Dennis Kelly, and Tim Minchin's songs are deficient in nothing except melody. It's a good stomping, syncopated score, with some incessantly intricate lyrics and some especially good choral numbers for the schoolchildren of all ages, but hardly a tune to savour all night.

The narrative adds a fairy-tale told by Matilda to the school librarian (Melanie La Barrie) about the lost child of an acrobat and an escapologist, and it rather muddles up the clean classicism of Dahl's conclusion. There's also a sudden incursion of Russian Mafia that over-complicates the exodus of Matilda's family to Spain, leaving her in happiness with Miss Honey.

But I have no complaints at all about Matthew Warchus's production, which is a "school's out" exercise in joyous liberation as Matilda – I saw the delightful, waif-like pocket dynamo Sophia Kiely, one of four girls rotating in the role – which pitches our heroine against the malign forces of her book-hating parents (one lyric rhymes Ian McEwan with spewin') and the child-hating gargantuan head mistress Miss Trunchbull, an athletic hammer-throwing former champion with a sadistic side-line in gymnastics.

Bertie Carvel has been rightly acclaimed in this role, which he manages to discharge as a glinting pantomime dame without going too far over the top. In the show's best stunt, he twirls a repellent student by her pigtails and despatches her to the gods; whence she falls with a vapid thump (illusions by Paul Kieve, natch).

The business with the rogue newt in her water jug, and indeed Matilda's sudden onset of telekinetic powers, are less imaginatively done. The lyrics during Bruce Bogtrotter's cake-eating feat are deliciously chewy but mostly inaudible. But James Beesley (the Bruce I saw, one of three) is just one of many outstanding singing and dancing juniors on show. Top marks and no detention for that lot.

If Lauren Ward wasn't so delightful as Miss Jenny Honey (is that a deliberate onomatopoeic inversion of Miss Moneypenny, I wonder?), you'd say Carvel stole the show. She actually makes Miss Honey as unselfconsciously nice as she is in the book, no mean feat. And she has the best voice in the show, too.

Mr and Mrs Wormwood, Matilda's ghastly parents, are splendidly caricatured by Paul Kaye and Josie Walker, the latter swopping her bingo obsession in the book for a theatrically obvious ballroom dancing habit and a snaky gigolo (Gary Watson).

You can't see the band – always a negative in a musical – but Chris Nightingale's orchestrations are top notch, and Rob Howell's design, beautifully lit by Hugh Vanstone, is a playground marvel of Scrabble-style letter blocks, huge swings, school gym equipment and Miss Trunchbull's green laser web for catching kids in the chokey.