What's the connection between the World Cup and the Bodleian Library? The august Oxford University institution is involving itself in questions more usually discussed in the pub, after being given the manuscript of the Rules of Association Football 1863. The scruffy original, which shaped the modern game, was given to the Bodleian by The Football Association and will now be stored by the Oxford University library among some of the most beautiful and valuable books in the world.

The manuscript, covering everything from the length of a regulation football pitch and the definition of a free kick, to the disgrace of wearing football boots with projecting nails which could injure another player, was written in 1863 by a group of Oxford and Cambridge University graduates, who met at the Freemason's Tavern in Lincoln's Inn Fields, London.

Now the Bodleian's book reproducing the rules is heading for the bestseller lists, having been launched at the perfect marketing moment. However, the rules first came to public attention long before the World Cup, when the broadcaster Melvyn Bragg included them in his list of 12 Books That Changed the World, launched at the Oxford Literary Festival earlier this year. He has contributed an introduction to the reissue, saying that without the rules, today's "beautiful game" and, indeed, the World Cup would have been impossible.

The marketing genius behind the idea of putting the rules into print was Owen Dobbs, of Blackwell's a bookseller par exellence. He wanted to promote all Bragg's 12 choices, and was amazed that there was no copy available of the football book. He said: "I'm an England fan, and I was traumatised by Chris Waddle's 1990 semi-final penalty." More controversially, he argues that Waddle's infamous miss against Germany, when he ballooned the ball into orbit' over the bar, would have counted as a goal under the original rules. Similarly, there would have been no debate about England's third goal by Geoff Hurst in the 1966 final. This is because the crossbar was only introduced in 1865, when a tape was first strung across the two goalposts.

To understand how an academic library became involved in questions which would seem less out of place in a pub quiz, we have to look back to September 2004, when the library published its first unlikely bestseller Instructions for American Servicemen In Britain reproduced from a 1942 US War Department handbook. Or perhaps, according to the Bodleian's head of communications and publishing, Samuel Fanous, we should go back to 1605.

"That's when we produced our first catalogue," he said. However, the library's publishing venture really got off the ground in the 1950s, when it started to produce scholarly tomes with titles such as Mughal Miniatures of the Earlier Period or Gold Tooled Bookbindings. They had a limited readership, particularly since the only place to buy them was the Bodleian's own shop in Broad Street.

When Dr Fanous arrived three years ago, he visited other venerable institutions to see how they handled their publishing operations. "I went to my colleagues in the British Library, the British Museum and the National Portrait Gallery and discovered what they were doing with their intellectual property, and they had flourishing publishing programmes.

"At the time, all our fulfilment was done by the library and we had no publishing catalogue, just a handwritten list. We took all our titles to a distributor and we got trade representation in the UK with Yale University Press and the University of Chicago in the US."

I asked the obvious question. Surely Oxford University already has its own publisher why not use OUP? "It's a sensitive issue and I would rather not discuss it," said Dr Fanous.

He added: "The library publishing programme does not try to emulate OUP. We are here to support teaching and research in the university. We publish things from our own collections. The Bodleian is an international library and we have an international reputation. Part of our mission is to bring the library to people who cannot get here in person it's outreach work." In the second year of trading, the new programme will not only break even, but may even make a profit. This is largely thanks to the Servicemen book, whose gems of wisdom have gone down well on both sides of the Atlantic. Its advice is somewhat dated: "You will find that English crowds at football or cricket matches are more orderly and polite to the players than American crowds. . . The best authority on all problems is the nearest 'bobby' (policeman) in his steel helmet. British police are proud of being able to answer almost any question under the sun. They're not in a hurry and they'll take plenty of time to talk to you. . ." The pamphlet emphasises Britons' good manners and soft-spokenness, and their dislike of "swanking" and bad language. "It isn't a good idea, for instance, to say 'bloody' in mixed company in Britain it is one of their worst swear words."

"We have sold almost 100,000 copies," said project manager Emily Jolliffe. "And almost 80,000 copies of Instructions for British Servicemen in France."

Like the football book, both are reproduced in a style reminiscent of the era of the original manuscript. However, the French pronunciation guide "bonjewer, commont-allay-voo" is as useful today as ever. And perhaps England's footballers could spend an evening before their big match digesting the words of Sir Bobby Charlton, England's best goal scorer, who contributes a foreword to the Bodleian's Rules book. He says the rules "instil admiration for the honesty, courage and skill of its players". He writes: "We should recognise that the rules do not simply make it possible to play football, they embody the spirit of the game."

Mr Dobbs, while pleased with the timing of the launch, says the book will sell long after the World Cup is forgotten. "I wouldn't be surprised to see it in JJB Sports or in Tesco. The FA is promoting it and it will be sold at football clubs. It should get some coverage on the back pages as well as the books pages."

The Rules of Association Football, Bodleian Library, £5.99.