David Walliams' exuberant adaptation of his most popular children's book does not disappoint.

11-year-old Ben (likeable Ashley Cousins) is sent to his Granny's every Friday night, so that his ballroom dancing mad parents (vivacious Laura Girling and Ben Martin) can enjoy Strictly Come Dancing on the box – especially the performance of star Flavio Flavioli (excellent Umar Malik).

Each Friday is predictable: a cabbage based supper, Scrabble, and early bedtime. Ben does not enjoy it at all. It's boring. 'Nooooooooo!!!' he cries, faced with another night in the company of a mauve-dressed, grey haired relative he hardly knows, and who his parents treat with little short of callous disregard or in his mother's case, scorn and minimal contact.

Walliams' story balances farce, gusto and grotesques with moments of finely balanced, deeply felt emotion.

However, when Ben comes across the sparkling contents of a Royal Jubilee biscuit tin, and realises that his Granny is not, like him, tucked up in bed but out and up to something, he becomes curious and engaged with the elderly lady for the first time.

In a glorious rap routine, the so-called gap between old and young falls away and Ben communicates with his Granny (superb Gilly Tomkins) perfectly, and she with him. Their timing, understanding and notes are impeccable: a team is born, and a heist is planned. Granny is none other than the Black Cat – a thrillseeking jewel thief. Ben is a would-be plumber – much to his parents' chagrin. Together the grandson and the granny pool their talents to steal… the Crown Jewels. The middle generation is bypassed. They don't understand.

The producers of the hugely successful 'Horrible Histories' have backed another monster child pleaser – but Walliams' story balances farce, gusto and grotesques with moments of finely balanced, deeply felt emotion.

Grandparents everywhere will be heartened in this tale of the discovery of rare worth; parents will be reminded of the need for contact and the hurt of isolation many grandparents face, and children may hope for more commonality than they'd anticipated with the elderly – regarding them with kinder, more generous and respectful hearts.

Terrific music which could benefit from some additional songs, a clever and inventive set and fast-paced direction all add to the fun of this production. When Gangsta Granny is no longer speeding across the stage in her Black Cat attire, driving her mobility scooter with verve and aplomb on a daring and dangerous mission – that's when Birmingham Stage Company's fine adaptation really hits home.

It's not forever – so cherish what you have – and look closer. Spangles aren't the real jewels: even the Queen knows that.