One evening a few years ago, I found myself at a Christmas party in London. The event took place on the eighth floor of a building in the heart of the City and, at one point, seeking an escape from the chatter, I took my drink and ventured out on to the balcony.

It was a clear, windless night. All around was a wonderful panorama crowned by the glorious dome of Saint Paul's in the distance. Then I started to look at the tall, glass-walled office blocks in my immediate vicinity. Although it was after 10 p.m., the lights were on in every building, enabling me to see into hundreds of offices. These offices varied in size and decor, but they all had one thing in common. Somewhere in every one of them was a desk on — or under — which stood a PC.

What then came to mind was the memory of a tousle-haired young entrepreneur named Bill Gates, who once articulated a vision of "a computer on every desk, each one running Microsoft software." What I was looking at that December night was the realization of that vision. Every one of the machines I could see was running Microsoft software: a software monoculture, if you like.