Beginning his career as a street magician, Lenahan moved to England in 1984. He also worked as a stand-up comedian and actor when he was asked to be the voice of Talkie Toaster. Lenahan would entertain the cast, crew and audience between takes by performing magic tricks.
In 1994, he became the first person in 85 years to be forcibly ejected from The Magic Circle. He had appeared on a television show called How Do They Do That?, where he had explained how the street scam Three Card Monte was performed. He argued that revealing how this trick was performed was a public service, but he was still thrown out.
He is a very popular corporate entertainer and has published three fantasy novels called the Shadowmagic series. He is also a past recipient of the title "Street Magician of the Year".