Preview: Ali Cook: Principles & Deceptions, Gilded Balloon

Ali Cook might not have fooled Penn and Teller, but the chances are his Fringe show will have audiences stumped. Here, he recalls the moment he challenged two of the world's best know magicians.

"I hoodwink people for a living. As a magician I pride myself on my ability to pull wool over eyes. But when I was asked to come up with a trick that would fool Penn And Teller for their ITV show I knew this was going to be a real challenge.

The reason for all the secrecy in the magic world is that once certain principles are mastered it's fairly difficult to fool a fellow magician. I had to come up with something ingenious. In the end I decided to go for the wow factor and perform one of the oldest recorded tricks in the world. It was originally performed in ancient Egypt by renowned magician Dedi who severed the heads of various birds and then resurrected them - re-attaching the heads.

My version uses a chicken and a duck and my trusty assistants Charlotte and Tia, who help me pull the heads off the live birds and swap them over - the duck ends up with a chicken's head and vice versa. Amazingly no animals are harmed in the process.

They say you should never work with animals. And to be honest the most difficult thing about performing this trick is working with the chicken and duck - Beyonce and Shakira.

On the day the atmosphere backstage was pretty electric. It was a real competition and we were there to win. Actually it was pretty exciting just meeting Jonathan Ross - but winning was important too.

Penn and Teller were incredible. Thoughtful and concentrated. They realised their task wasn't an easy one and understood the time and energy which had gone into crafting each magician's routine.

When we had performed the routine (all performed live so there are no second chances) I was thrilled to hear Penn Jillette say he was blown away by the trick. P&T thought they had some idea about the principles of how the trick worked so I had to concede that I hadn't fooled them. Although I bet if I had asked them to draw a diagram with a detailed bullet point explanation they would have been stumped. Not that I'm a bad loser or anything."

Ali Cook: Principles & Deceptions, Gilded Balloon, Dining Room, until August 28, 9.30pm, 12-13, 0131-226 0000