Nick Hornby is thumping his fists against my chest and screaming: "Go away, I don't want to talk to you". We're standing outside Dublin Airport's departure lounge and a group of passengers looks on with interest. "I'm not talking to you," Hornby screams again, and a serious-looking man is about to intervene in this famous-author-in-interview-rage situation.
All Hornby was actually doing was giving a verbal and physical description of how his eight-year-old son, Danny, reacts when people he doesn't like come into his house. "I'd love to be able to react like that with some people I know," he says with a crumpled smile.
He's talking about Danny, who is autistic, because he's just been talking about selling the film rights to his books. "As far as I'm concerned, if someone is going to come up to me and offer me loads of money to buy something which I've already been paid for - the book - then I'm willing to do it."
Such is his stature now that the rights for his last but one book, About A Boy (named after a Nirvana song), were bought by Robert De Niro's production company for £2 million.
The film, with Hugh Grant in the lead role, will be out next year. "I just think it would be an incredible prissy not to sell on the film rights, particularly if you've some idea about how you want to spend the money," he says.
His son was diagnosed at the age of three and Hornby has talked openly about how the strain of bringing up an autistic child was a "huge part" of the reason for the break-up of his marriage. "We would both say that Danny is the best thing in our lives and brings us so much pleasure, but autism does place a strain on relationships."
His son's condition has irrevocably changed what he does with his time and money - he devotes both to raising public awareness of the condition and securing the funds to support a purpose-built school for autistic children in north London.
Although he's loath to ever write about his son - "at least not in fiction form", he does allude to the fact that the inspiration for his new book, How To Be Good - in which a man undergoes a radical spiritual conversion - came from the letters he receives from "well wishers" who suggest possible treatments for his son. "Spiritual healers and homeopaths mainly. Putting his head in a bucket of cabbage. That sort of thing."
Although it's eight in the morning (the middle of the night, if you ask me) and he was out late the previous night with his close friend, Roddy Doyle, he's in chipper form. Dressed in the fortysomething uniform of crumpled leather jacket and jeans, he looks like the English teacher he once was.
His PR person tells him his new book is "number one" in both Ireland and Britain this week, but Hornby's more interested in talking about the League Of Gentlemen and the new Radiohead album. Five minutes in his company and I unilaterally decide that it would be philosophically impossible to dislike him.
When I find out that Teenage Fanclub are one of his favourite bands and that he knows the real reason why Tony Currie left Leeds for QPR in 1979 (a pivotal moment in many people's lives), my critical faculties desert me entirely.
It's too early to be talking about literary stuff, so we have a "best album of the year so far" confrontation (his is the Los Lobos box-set) and he bemoans the fact, that as music critic for the New Yorker magazine, he has to write 2,500 words for every album review.
When he eventually gets around to talking about his books, it's through musical comparisons. Talking about Fever Pitch (his breakthrough autobiographical account of life as an Arsenal fan), he says he was thrilled when a reader from the US told him that he totally understood his feelings about a football team, because that was how he felt how about Bob Dylan.
"That's great, isn't it," he says, "but I can't help thinking if you're a Dylan fan what would be your equivalent of losing the 1978 Cup Final to Ipswich - which was one of the worst moments ever. Would the equivalent be Dylan releasing the Self Portrait album?" He stares intently out of the window of the cab taking him to the airport and finally concludes that nothing in Dylan's career could compare to the 1978 final.
Born in 1957 in Maidenhead, the son of a successful businessman, Sir Derek Hornby, he studied English at Cambridge University, but really it was more like "sitting in the pub, smoking and talking about football and The Clash". He begrudgingly taught English at a comprehensive school after graduation - "I had no ambitions for myself whatsoever before I was 26 or 27". He started writing book reviews - "we took him on because we felt sorry for him" says one of his ex-editors - before packing in teaching and sitting down to write about his dysfunctional relationship with Arsenal FC.
He thought Fever Pitch would sell, but only among Arsenal fans: "I thought that if people are prepared to spend £24 on an Arsenal duvet cover, then they might be interested in spending £14 on a hardback". The book's massive crossover success - which inspired a rash of "me too" confessional tomes - has created a new literary term: "Hornbyesque".
"I think it's well-documented by now that I was not and never have been a 'lad' writer. That may have hung around for a bit because High Fidelity was about music, but I was doing a signing for this new book and this woman was there who only started buying my books with About A Boy which really pleased me."
The received wisdom was that after his two "popular culture" books, there was some sense of "real" literary merit to About A Boy. Hornby couldn't care less, saying it loud that he's middlebrow and proud. "Some of my favourite middlebrow novelists include Dickens, Steinbeck, Ann Tyler and Jane Austen. I don't really want to be distracted by a book's brow. I want to look it in the eye".
A close friend of Helen Bridget Jones' Diary Fielding, he says the two of them expected more of a backlash from the established literary community to their envy-inducing levels of commercial success.
"If you really examine it, this 'establishment' is only about 23 people. And anyway, I've had some of the most 'highbrow' writers come over to me and say how much they enjoyed such and such a book. I was at an event in New York and sitting at the same table as Edmund White and I honestly thought he would never have heard of me, so I was astonished when he told me how much he liked High Fidelity."
For the past month, he's been on a dizzying promotional tour for How To Be Good: "all hotel rooms, signings and interviews". He enjoys it all he says, but if you push him on it, he confesses that he jumps through all the promotional hoops held up for him because he feels he has to justify the advance from the publishing company.
"I suppose now I'm getting about 300 to 400 people in for the readings which means that it can't be done in a bookshop, it has to be done somewhere bigger. The people who come along are great, except sometimes you'll find yourself in a place in Texas and this guy will turn up wearing an Arsenal T-shirt and his first question is always going to be something about Arsene Wenger and Patrick Viera - which isn't much use to everybody else there."
There's the odd nutter to contend with. "That usually only happens in Germany for some reason. The last time I was there at a signing, some guy came along and asked if I could sign a book. He then proceeded to open up this big sports bags which contained all of my books, a lot of them translated and some of them film tie-ins with different covers. There were loads of them. And I was thinking to myself "if someone is going to kill me, it's going to be him".
Reverting again to musical matters, he says that he feels like the "R.E.M. of the book world", thanks to his huge sales figures, but before we can discuss this interesting use of simile, he has to run for his plane - "I'm going to a big warehouse this afternoon to sign loads of book plates".
Which is a shame because I wanted to tell him that he never had a Document or Green period, his first book was an Automatic For The People, which invalidates the comparison. Now if he had mentioned New Order ...
How to be Good by Nick Hornby is published by Viking (£16.99 in UK). It is reviewed on Weekend 14