But taking a favourite novel, and cutting and rewriting it, is tantamount to heresy. So when Vicky Ireland decided to produce a stage adaptation of Double Act by classroom favourite Jacqueline Wilson, she knew that she had to tread carefully. “It’s nice to give children their favourites occasionally, rather than what we think they should be reading,” the writer and director said. “But we need to listen to them. Adults can so often botch things.”

In fact, Double Act, which is being performed in London before a nationwide tour, stays almost self-consciously true to its source. Scene-setting has been sacrificed in favour of snappy plot development, but much of the dialogue has been transferred intact.

And Ms Ireland worked together with Nick Sharratt, long-time Wilson illustrator, to ensure that the set accurately reflects the spirit of the book. There are bright, primary colours, pop-up cardboard props, and a series of visual in-jokes taken directly from the page.

Double Act is the story of identical twins Ruby and Garnet Barker. After their mother’s death, the pair take comfort in their doubleness, creating a joint identity that compromises them both.

When their father finds a girlfriend and moves them all to the country, the twins form a united front against change. Ruby bullies Garnet into running away to London and applying to boarding school. But when only Garnet wins a scholarship, they have to face the possibility of life apart.

There is no melodrama, no evil stepmother or cruel deprivation. But the upbeat dialogue masks serious concerns, including death, sibling rivalry, moving home and changing schools.

“These are very traumatic issues,” said Ms Ireland. “But there’s a great kindness and affection in the story, which makes it all more palatable.

It’s a brilliant way of talking about difficult emotions.”

Adopting the mannerisms of 10-year-olds, the adult actors playing the twins could easily have slipped into twee parody. But their enthusiasm is genuinely childlike, and surprisingly convincing.

Nine-year-old Rebecca Norfolk, among the audience in London, said: “At first I knew they were grown-ups. But then I thought, whoah. That’s like me!”

Jacqueline Wilson is similarly impressed. “This is fresh and energetic and should not disappoint fans. Stage plays are such a difficult art, but this is how I would do it,” she said.

www.doubleacttheatre.info