As the children in CBBC’s Help! My Supply Teacher is Magic all find out, there’s something wonderfully shocking about discovering that the adult at the front of the classroom is actually a magician, and not a teacher after all. But bringing the hit TV show to the stage poses a fundamental problem: simply by virtue of buying a ticket, the game’s already up – you know full well who the performers are. But never fear: magic being what it is, though, there’s still plenty left to shock and surprise you.

‘The nature of magic is one of inherent surprise,’ says one of the show’s magicians, Cardiff-based sleight of hand expert James Went. ‘At the outset of a trick, the audience doesn’t know what’s going to happen, but they then experience surprise when an impossible quality is demonstrated, such as levitating. There are many elements in the live show designed to do just that, so audiences will get the same kick as on TV, but amplified.’

Being naturally curious, and possibly unaware of the Magic Circle’s famously strict code of ethics, children watching the show will no doubt want to know how it’s all done. How do Went and his fellow magicians deflect the awkward questions that they get after performances?

‘We do get asked a lot, and I’m genuinely interested to find out how the children think the tricks are done,’ says Went. ‘Kids are really smart and have the ability to think in a very logical way, which is normally forgotten by the time we reach adulthood.’ But what if they can’t figure out a trick by themselves? ‘Normally they’re very respectful when you simply say, “I’m sorry, I can’t tell you.” However, in more pressing situations I’m glad to say I can generally run much faster than they can.’

Underbelly, Bristo Square, 0844 545 8252, 3–25 Aug, 1.10pm, £11.50–£12 (£10–£10.50). Previews 1 & 2 Aug, £6.