Ben finds Granny so, so boring he dreads being left at her house every Friday night. Yes, she’s very kind and loving but Scrabble and an early night are all the excitement in store for poor Ben. Still worse, the shuffling, mobility-scooting oldster has such an overly obsessive obsession with cabbage that the pungent leaves feature in every recipe of every course of every meal, right through from cabbage soup to cabbage crumble with cabbage-y, cabbage-y custard. It comes as no surprise that this hefty brassica overdose gives niffy Nan an explosive, farty flatulence that trumps even that of the great Petula Gordino. But is there more to Ben’s granny than meets the nose? How come her old biscuit tin is heaped full of precious jewels? What else is she hiding?

Gangsta Granny (2011) is the fourth book in David Walliams’ prolific output of top-selling children’s stories. His unsophisticated prose style, like Granny’s cabbage, may not be to all tastes, but his outrageous plots and silly stories get kids worldwide laughing and reading. The 2013 BBC film of the story was a triumph for Julia McKenzie, with a fine cast that included Joanna Lumley as The Queen. The Olivier nominated stage version, adapted by Neal Foster, has been going strong for a good few years now, though script, characters and continuity are not, for the most part, as smoothly coordinated, well rounded or gripping as the film.

Convincingly stooped and shuffling, Isabel Ford plays Granny wonderfully well, creating a warm, caring, endearing old nan with a twinkle in her eye that’s full of eccentricity, devilment, adventure and well kept secrets. Grandson little Ben (11) is beautifully and enthusiastically played (as a reasonably-sized big Ben) by Justin Davies. His glorious Welsh Valleys’ accent doesn’t seem to puzzle his non-Welsh-connected parents in the slightest. The chemistry of the burgeoning relationship between erstwhile boring, but suddenly exciting Granny and her plumbing-mad grandson is crucial to the drama and works a treat. The other characters are less well defined and complete, while cast changes and the shouty, proclamatory delivery in the first act don’t help. The audience certainly take, though, to creepy neighbour, Mr (nosey) Parker, played by Jason Furnival as a convincingly villainous baddy with a Brummie accent as thick as that of William Shakespeare’s father (as portrayed by Harry Enfield in Upstart Crow, at least.)

Since Ben’s self-absorbed parents are thoroughly obsessed with Strictly Come Dancing there’s plenty of dazzle and bright colour on offer, and, in a ballroom competition spoof, we’re treated at last to some really fine, exciting dancing from tonight’s young addition to the cast, who adds elegant leaps, splits, acrobatics and sunny smiles to her delicate, delightful routine.

Jaqueline Trousdale’s admirable set presents building blocks of brick, stone and windows that rotate and open up to whisk us neatly from granny’s cluttered parlour to Ben’s bedroom, to hospital ward, to glitter-ball ballroom or to the Tower of London and the glistening Crown Jewels. Scene-shifting cast members blend into the drama in multiple costumed roles as Jak Poore’s music plays, the fine instrumentation of his score creating bright sparkle time and again and, when required, some pianistic pathos.

The Birmingham Stage Company are old hands at entertaining children (think Horrible Histories) and there are smiles all round from the young audience, as well as sympathy for Ben’s lovely Granny and also, perhaps, valuable insight into the fact that most old people have led pretty rich and eventful lives in the run-up to becoming the slowed-down elderly person they now see before them. A heart-warming tale, then, with plenty of silliness and a touch of sadness.

Eileen Caiger Gray

The show tours until July to Hull, York, Woking, Truro, Wolverhampton, Tunbridge Wells, Nottingham, Shrewsbury, Torquay, Blackpool, Chester, Exeter, Poole, Oxford, Belfast, Barnstaple, Glasgow, Dublin, Darlington, Richmond, Peterborough and Aylesbury. You can find out more by following this link.