When he is tested, Andi - the 2002 world memory champion - correctly remembers the position in the packs and the value of every single card he is tested on. So how does he do it?

Andi's technique is an unusual but simple one. Long before taking on any memory challenge he walks past a set of London landmarks, establishing the route firmly in his mind.

He might start at the Houses of Parliament, before continuing to the London Eye via Westmister Bridge.

But that's just the first stage. The second involves using a bit of imagination.

Once you learn a technique like the location technique it takes everything beyond what you can do naturally

Andi Bell: "When I memorise a deck of cards, I turn each card into a picture and this is a colourful animal or object that I've learned to associate with that particular card," Andi explains. “The jack of clubs might become a bear, the nine of diamonds a saw, and the two of spades a pineapple.”...