Roald Dahl’s books remain so incredibly popular across generations, because they have a deliciously dark streak. And they don’t get much darker than his classic George’s Marvellous Medicine.

The story sees George’s mean-spirited, overly demanding granny coming to stay and driving everyone crazy. He decides to get his own back by concocting his own witch’s brew made out of things found around the family farm. The results, suffice to say, are hair-raising.

Director Julia Thomas’s production, by Leicester’s Curve and Rose Theatre, Kingston, stretches out that concise tale into a lively two-part show aimed at young children but which was entertaining to all.

The five-person cast are sparky and engaging. Lisa Howard is brilliant as the annoying northern grandma and an energetic Preston Nyman is fabulous as George – his home chemistry sessions in which he concocts, then fails to recreate, the medicine are as marvellous as the title suggests.

What elevates the production to a different level though are the effects – the glowing concoctions, fizzing and smoking, a model chicken whizzing across the stage, and the spectacle of grandma stretching skywards.

Attempts at audience participation delighted the younger audience members who hollered their heads off, lending it a sweet panto touch – and it even ended on a song – with the take-home message: “don’t try this at home!”

It is a high quality show, with excellent production values, credit for which must go to designer Morgan Large – for the chaotically elaborate stage set laden down with dastardly jars of ingredients and a brilliant outside loo – and lighting designer Jack Weir for those glowing buckets of nastiness.

It’s all fun and really aimed at primary school age kids.

And if your children offer you a spoonful of anything after watching this, I’d very politely decline.