Balthazar and Pastis are among New York's hippest restaurants, but their French-inspired appeal is all down to Keith McNally - a former bellboy from London's Bethnal Green.

Balthazar, the Parisian-style brasserie just around the corner from the new Rem Koolhaas-designed Prada and Guggenheim in downtown New York, is a barometer of the city's self-confidence. For most of its five-year history, if you wanted to dine there on, say, a Tuesday, you'd need to book three weeks in advance. And it's not as if it's small. But 11 September dented New York's brio, and made an awful lot of people feel cautious, pensive, unwilling to be seen to be having a good time. Keith McNally, the restaurant's British owner, was gloomy about the its prospects when I first spoke to him last January. There wasn't enough noise at lunchtime, he grumbled: you could hear yourself speak.

By the time I was next in New York, only a few weeks later, normality was beginning to reassert itself. The 180 tables and 25 seats at the bar were in demand again; Balthazar and New York were evidently back in business. Now, of course, there are sliding stock markets to contend with, but as the anniversary of 9/11 approaches, McNally is back again as one of the most fashionable restaurateurs in what remains the most buzzing, thrilling city in the world.

Not bad for a boy from Bethnal Green. Keith McNally would object here, and scathingly, that this remark is typically British. Not that he needs to worry: when he met me for lunch recently he was wearing a cashmere sweater over a T-shirt, had the sort of haircut that shouts 'seriously stylish rich person' and generally looked like what he is: one of New York's most astute, culturally attuned entrepreneurs. But he left Britain partly because he loathes the way the British care so much about where you come from. And it only takes a question about his background to launch him on a tirade: 'I have a very uneasy and ambivalent attitude towards England. There's a side to it that I find petty and squalid and class-ridden. And to me it's symbolised by the archaic and totally hypocritical judicial system.

'The Jonathan King case. He got seven years, and for what? For touching the private parts of 15 year-old boys! To me that's a draconian sentence. Draconian. Fifteen year-old boys are not angels. Half of them are bashing in the heads of other football fans, the other half are masturbating all day. Eight, nine, 10, 11 - that's totally different. And all of it happened 30 years ago.

'I was one of those boys. I went back to his apartment when I was 16 or 17. Big deal. Nothing much happened. What I remember most was that he was quite erudite and very, very witty. If he was going to get seven years it should be for his bad music - but touching boys: who cares? 'I'm surprised by those people who came forward saying they've been affected by him for the rest of their lives. I had that experience with him, and nothing was forced. I haven't suffered in any way at all. I really think I've benefited from those few visits over to his house. He's a very funny guy.'

After this, both because of the content of what McNally has said, and the vehemence with which he's said it, it is rather difficult to get back to restaurants. 'I'm sorry,' he apologises. 'I could go on about this all day. It did me no harm. If anything, the opposite.'

But even without the digression, McNally wouldn't be a particularly easy interviewee. He avoids meeting my eyes for at least half an hour. He prefers to answer questions with a joke. He fends off questions with a heavy irony that I want to warn him - except I'm not sure he'll take it kindly - doesn't work in print. It is hard, initially, to warm to his jerky way of speaking and apparent lack of interest in his career.

But as lunch proceeds, and when I meet him again over breakfast at his latest venture, Pastis, I realise that his apparent offhandedness derives from a wish not to take himself too seriously. His habit of deflecting questions and his deadpan humour arise from self-deprecation and a dislike of hype and pretension - and it's this, I think, that is the key to the enduring success of his restaurants.

The son of a stevedore in the London docks (who later became a taxi driver), and an office cleaner (who learnt Spanish at the age of 40 and became a secretary), McNally is the third of four children. 'There was a lot of acrimony. No one in my family's ever really got on.' (He has, however, worked with both his older brothers at different times, and his 82-year-old father has recently arrived in New York to live with him.)

After grammar school - Cooper's Company, where 'I didn't distinguish myself in any way. I probably wasn't very clever' - he became, at 16, a bellboy at the London Hilton Hotel. 'I had no ambition for the industry. I don't think I went into a res