Frances Hodgson Burnett, author of The Secret Garden, was the J K Rowling of her day.

Her 1910 novel fused together almost as many memes from childhood stories as Harry Potter – there’s the orphan girl (Jane Fairfax from Emma, Eppie in Silas Marner), the lost child of Empire (Kipling’s Kim) the invalid who struggles to walk (Clara in Heidi), the ferocious governess (pick any one you like in Dickens), the furious child too wild for Yorkshire school (Jane Eyre), but also Wuthering Heights for t’windswept mansion on t’moors with muffled sounds of crying from th’attic.

Throw in a jigger of Edwardian melodrama with a brooding hunchback, a ghostly ‘Woman in White’ wife straight out of Wilkie Collins and a doctor who may be manipulating his patient to receive an inheritance and you have quite a rich cocktail for the ‘book’ of a musical, where ungracious characters are salved by human contact and the spiritual rebirth of a garden. Get Alan Titchmarsh on board as technical consultant and you might have a winner.

With a crisper lyricist like Tim Minchin and a less diabetic layer of glucose sentiment you could have a second Matilda but not, regrettably at the hands of Lucy Simon whose music is aimlessly repetitive and Marsha Norman whose lyrics could win a lifetime achievement award at a festival of banality. It’s astonishing that she also scripted The Color Purple.

If you are going to stage even a 75-minute truncated version of this musical surely the minimal requirement is a ‘garden’ since it’s both the setting and the metaphor for the entire conceit.

Camped out in the daytimes and off-nights for the Australian percussion musical Stomp whose scaffolding and drum equipment is scarcely concealed, there’s no chance for the set designer to demonstrate green fingers, and a pathetic net of dahlias and poppies – which have different blooming seasons – is all that’s available to represent Eden.

No-one is evaluating this show as a genuine ‘West End opening’ because it is a directorial exercise mostly in crowd control and opportunities for the young cast members, 300 of them rotating the 24 roles, to tread the boards of a real live West End playhouse under the aegis of the British Theatre Academy. But if you put a school play on at the Palladium it would still be a school play.

The choreography is as horsey as a Newmarket stable yard yet there’s a certain triumph for Jamie Neale in teaching it to three hundred young actors – but other than youth employment it’s hard to divine the purpose of the ensemble who repeatedly shuffle sideways on and off in the cramped space and billowing dust sheets over the furniture with much anxious ‘am I in the right place’ eye-swivelling.

Of course the worthiness of purpose transcends the production values – with so many mums and dads in the audience, an enthusiastic reception is guaranteed and it matters little that the baronial hunchback’s voice seems derived directly from Mr Clifford in Acorn Antiques or that the white gloved soprano perpetually inviting all comers into her lady garden is only a tiara short of Princess Margaret in her dress and coiffure.

Alana Hinge made a competent Mary Lennox on press night, and it’s the script and music that makes the characterization somewhat shouty and one-pitch rather than any failings in her performance, but the junior acting honours and the best laughs went to Sam Procter as Colin, transitioning perfectly from bedridden tyrant to young charmer.  Samantha Bingley added a layer of comedy class to stereotypically-written maid Martha, and Matthew Nicholas as Dickon and Joe Edmunds as gardener Ben each made these horny-handed sons of toil come convincingly off the page.

The ensemble singing has great warmth and charm: I just wished they’d borrowed ‘Make Your Garden Grow’ from Candide as a finale.