Three days into my declaration of allegiance to West Ham, I already managed to provoke serious angst in other football fans (although you’ll be pleased to know that I’ve yet to get punched). Most piqued, perhaps, was my friend who shall henceforth be known as The Liverpool Fan.

Every year TLF’s mother gives him a Liverpool calendar for Christmas and he hangs it in his kitchen. Last winter, when I was having some romantic difficulties, we would stand in his kitchen for hours drinking tea, discussing the romantic difficulties, and occasionally asking the Liverpool player of the month for advice (‘What should she do, Jimmy Carragher?’). TLF is not impressed, therefore, that I have not thrown my lot in with his boys.

‘All the times we asked the calendar for advice,’ he said. He is a joker, it is true, but he was also genuinely perturbed. ’How could you? Besides, you can’t just pick a football team by asking people on the Internet who to support - it’s like saying, “I’ve decided to pick a new religion, which one should I choose?”’

Which is, of course, exactly the kind of attitude that inspired me to pursue this project. I never would have questioned that part of the motive that inspires people to commit themselves for life, wholeheartedly, to football teams is similar to that which drives them towards religion, but I want to discover which kind of group is easier to join - and exactly how much they have in common.