Let's start by saying that this is a nice idea. Two double acts bounce off each other on stage, sparring with words and jostling for audience attention. The twist is that one act is made up of of two adults (creators Christopher Brett Bailey and Jessica Latowicki); the second pair consists of two children (Caitlin Finlay and Caspian Tarafdar).

There is no obvious narrative to Double Double Act as such; instead the show offers a series of sketches, of variable quality. They're loosely linked by the children's double act being similarly dressed and performing as mini-me versions of the adults. Old-school telephones are a recurring theme, punctuating and interrupting the action by turns. The opening phone sequence is promising, with the assured youngsters engaging impressively with the audience right from the start, and earning some genuine laughs to set the mood. Director Tim Cowbury's hand is evident at this early stage.

We then meet our adult duo, who engage in a torrent of music-hall style wordplay, a form that some may feel has limited appeal for children. Then a supremely unfortunate (and repeated) reference to ‘making out with babies' kills this section stone dead for the grown-ups, at least. If the children in the audience seem bemused, they're soon brought back to life by some good, old-fashioned poo and fart references, proving once again that toilet humour never fails to delight six year-olds.

In fact farts are on standby whenever the mood flags, with some green slime held in reserve for a later highlight. It's the slapstick sections of the show that are by far the most successful, and the energy that accompanies the chase on a variety of bouncy and wheeled vehicles is exhilarating and entertaining.

Bailey has considerable comedic gifts, as well as a near-demonic gleam in his eye. If he's setting out to be an unsettling and rather scary figure, he succeeds. Latowicki is sparky and engaging, but she's saddled with rather too much of the ‘dark humour and deadpan dialogue' the company says it uses to ‘excite and unsettle' its audiences. Designer Emma Bailey's set has plenty of fizz, while Alex Fernandes' lighting design contributes considerably to the atmosphere.

Creators Made in China may be hoping children will leave the show eager to discuss the issues of violence, misogyny and depression that are touched on during the performance, but it's much more likely that the only things that will really stick are the chasing, the slime and the cat poo.

And in truth, they are the best bits.

Double Double Act runs at the Unicorn until 9 July.