Amore incongruous sight would be hard to imagine, particularly in 1951. There, at the heart of a vast catering empire devoted to tea and cakes, was a pulsing sci-fi monster with endless rows of tubes filled with half a ton of mercury. The monster's name was Leo. It was the world's first business computer and its master, David Caminer, who has died at the age of 93, was one of the great pioneers of commercial computing.

Sixty years ago, nobody would have seen anything like Leo. Official secrecy meant that the public knew nothing of the spectacular progress made by British scientists in developing the code-breaking digital computer, Colossus, which helped win the second world war. Civilian computers did not exist and nor did the software to run commercial applications. Caminer was the intrepid, determined person who invented the first business programmes.