If there is a single point at which today's global IT industry was born, it could be argued that it was on the 17th November 1951, when LEO, the Lyons Electronic Office, ran the first business application on an electronic computer. 50 years later a conference was held in London to mark the `50 years of business computing'. This article is based on the 2001 Pinkerton Lecture given on the 5th November at the conference by the author, who was manager of J.C. Lyons Systems Research Unit.