Bum. Wee. Fart. Willy. If you’re not yet helpless with laughter, you’re probably over ten years old. This show has an obvious head start in pleasing its target audience - children of primary school age - which Andrew Jones as the bald prof and Ciaran Murtagh as his goofy assistant Willy Whee build on with frenetic inventiveness.

The premise is that the story machine of the title - a homemade-looking construction covered in knobs, tubes, hatches and flashing lights - breaks down when Whee spills his coffee into it so, instead of demonstrating its wonders to an audience of boffins (us), the duo have to substitute their human storytelling skills.

Fresh from a successful run in Edinburgh and with several years’ experience of improvising together, the pair seem able to anticipate each other’s thoughts. Which is just as well: improv is a risky business. But, willing to hurl themselves into mad roles and madder wigs, to test and trick each other with random props and sounds and to say whatever comes into their heads (sometimes in rhyme), these two are never short of an anarchic idea.

Every hour-long performance is different as half-a-dozen stories and poems grow from words provided by the audience. If I were going to bother to be a serious adult critic here, I’d say that the one about the walkie-talkie wasn’t really effective, and the tank engine finale fell apart as a story, but that would be to miss the point.

Kids around me were rolling about in delight with their attendant adults chuckling along. After all, what does structure matter when Whee suddenly has to integrate a trainee zebra genie into a pop-singing competition or when prof and sidekick become an instant ramshackle engine with the help of a few hoops and some painfully deployed cardboard tubes?

Take the kids, rediscover your (preferably silly) inner child and enjoy. The message on this occasion? Don’t put cardboard tubes down your trousers. You know it makes sense.

- Heather Neill