So for the first time I've managed to watch Ben Hanlin Trick on ITV2. One trick he perform was... Ben Hanlin got into a London black taxi and said to the driver take me to a London landmark. After telling the driver where to take him, he directly handed the driver a white envelope. Once arriving at the landmark on London's Embankment Ben Hanlin got out of the taxi and said "do you remember the white envelope i gave you at the start open it". So the taxi driver did and to his surprise it was the exact fair that he had to pay. Amazingly done

I really want to know how it was done. But I also know we aren't allowed to discuss the workings of a trick. If anyone knows how it was done please advise what DVD teaches you such performance. Or was it just a stooge?