Opening a stack of circulars and credit card solicitations this weekend, my thoughts turned to the late Edgar F Codd. The British mathematician, who died two years ago, was the father of “relational” databases, today used by government agencies looking for signs of terrorist activity, retailers analysing weekly sales figures and credit card companies deciding whose mailboxes to stuff.

It is hardly an exaggeration to say that Ted Codd’s invention changed the world. Until the early 1980s, when his ideas were widely adopted, data was mostly stored in “hierarchical” databases that were both inflexible and difficult to interrogate without a PhD in computer science. The relational model, based on an easy-to-analyse system of rows and columns, made it possible to identify quickly, say, customers in California with two children and size 11 feet.