I heard a presenter on XFM talking about the recent series of Hell's Kitchen, and he said, 'I don't know who that chef guy was but he was very good', and someone else piped up, 'I think he's the man who trained Gordon Ramsay'. Oh Marco, I sobbed, has it come to this? He was the youngest ever chef, at 33, to win three Michelin stars and the first Briton. He was our one-man answer to French gastronomic complacency because he had never trained in France. In the Eighties and Nineties he bestrode the British restaurant industry like a colossus. And now he is 'the man who trained Gordon Ramsay'- it is tragic. But it is his own stupid fault: he retired from cooking on 23 December l999, handed back his three Michelin stars, and since then has squandered his reputation in a bewildering succession of short-lived business ventures.

I first interviewed him back in 1992 when he was still at Harvey's in Wandsworth, the restaurant that made his name. He was gorgeous in those days, very thin, staring-eyed, and fiery, but almost unintelligible. He spent hours expounding his 'philosophy of life', which seemed to consist of baffling aphorisms like 'Only dead fish swim with the tide'. Presumably it went down well with junior staff and models (he was a great modeliser in those days) but a bit wasted on me. Anyway we 'go back a long way', as he keeps telling me, while pouring compliments over me like custard. The only thing that slightly spoils the effect is that he later goes into a paean of praise to Rosie Boycott that makes my portion of compliments seem somewhat meagre by comparison.

Unfortunately Marco has developed a whole new concept in making life difficult for interviewers. He keeps saying, 'On the record but not for publication', which seems to mean that I am allowed to keep the tape recorder running but am supposed to - what? - lock his secrets in my bosom? Deliver them to the Public Record Office for release 30 years after his death? Bah, humbug. It is not the job of journalists to keep secrets. But it means that he keeps half-telling me things then refusing to explain. For instance, he told me, 'on the record but not for publication', that he no longer owns his own brand name: 'I gave it to a trust to ... So if you want to do a deal with me, you don't deal with me. I can't go into details. But it's simplified a lot of my life.' Perhaps this explains why he disappeared from the Sunday Times Rich List a few years ago.

We are lunching at Luciano's, a restaurant he co-owns with Sir Rocco Forte, which used to be Prunier's, in St James's Street. It is a glorious art deco room but puzzlingly empty - for much of lunchtime we are almost the only customers. Marco is thrilled when an elderly lady arrives in a hat. 'Oh I love ladies in hats!' he exclaims. 'One rule of restaurants: never take a hat from a lady; wait for her to offer you the hat because she might not want to take it off - she might not have had time to do her hair properly.' This is typical of Marco's persistent enraptured infatuation with the upper classes - I have never met anyone, let alone anyone from a Leeds council estate, so uncritically devoted to the ancien regime

He asks a waiter for the menu and reads it as if for the first time. 'Why is this starter £6.20?' he wonders. 'I can understand £6.50 or £6.95, but not £6.20.' But this is supposed to be his restaurant - it is named after his eldest son - so why doesn't he know? Apparently he doesn't do the money side - Rocco Forte does all that. Anyway, he quickly orders riboletta (bean soup) and fettucine for himself and tells me to have the veal cutlet, with zuccini on the side, and crab with 'pane caude' to start with. Pane caude turns out to be some sort of crispbread rolled like a brandy snap, which makes it completely unsuitable for sopping up crab. I can't believe the old three-star Marco would have approved.

He orders a glass of champagne for me but not for him. 'I don't really drink,' he tells me, and looks stern when I laugh. 'Think of all the times you've met me, you've never seen me drink. I never had a drink at all till I was 38, I'm just not a drinker. I go days without drinking. Only journalists sometimes get me drunk!' Is this right? I've never had a sober meal with Marco but, come to think of it, maybe that's just me. On the other hand, when I ask for a glass of red later, he orders a bottle of Bardolino Classico and seems quite happy to share it - 'It's a little wine from my mum's village, and I always think if it came out of the same ground as my mum, it must be good'. His mum, of course, is a constant companion in any Marco conversation. When he recently had 'words' with Angus Deayton, who presented Hell's Kitchen and made some disparaging remark about his name, his parting shot was, 'Angus, the eyes you look at are the eyes that watched my mother die'. Deayton was understandably perplexed but anyone who knows Marco knows that he habitually uses his mother's death as his Get out of Jail Free card. He saw her collapse with a brain haemorrhage when he was six and that explains and excuses everything.

A customer comes over to compliment Marco on Hell's Kitchen and I warmly pitch in, saying truthfully that I loved the show. But Marco is very sniffy at first and says he hasn't even watched it. He claims he was first asked to do it four years ago - before Gordon Ramsay - and only agreed this time 'for my kiddies, because they'd never seen the old man cook'. But it was his first time in the kitchen for seven-and-a-half years - wasn't he apprehensive? 'I don't think like that. I went there to do a job and my job was to feed 76 people every night and sometimes 100 people with what I'd been given. And I proved to myself that I can still do it. I might not be as fast as I was - my boys said that I was 35 or 40 per cent slower than I used to be - but if I was that fast, I'd have left the celebs behind.'

It was a long hard stint. For a month he was living and working in this strange telly bunker in darkest east London, away from his family and with his mobile phone switched off. He reckons he worked at least l8 hours a day, starting at six and finishing at midnight. The previous Hell's Kitchen chefs, he sniffs, didn't work nearly such long hours and had prep chefs round the back but, 'I didn't. I led from the front. Sometimes I took such a bashing on that pass - you'd got all these tickets and all this food to serve and I'd put one ticket in my mouth, one over there, one over there, so that it didn't look so monstrous.' He had just two experienced assistants, Matthew and Tim, who've worked for him since they were l8, and then 10 assorted celebs as his brigade.

He had no say in choosing the celebs, and still seems a bit vague about who some of them were. But right at the beginning he gave them the task of cooking an egg, which allowed him to assess their basic competence: 'You can tell by the way they crack it, they hold the pan, by the way they stand by the stove.' He found Jim Davidson most reliable: 'He was the person that from very early days I could turn my back on in the kitchen and know that what he did was right. He's very bright and he enjoys cooking - he cooked for the staff most days.' And he loved Rosie Boycott: 'She was my favourite - interesting, intelligent, a proper person, and I remember the day she was voted off I was very sad. She was a lady.' But they were all good, he says, because 'In the kitchen they're no longer celebs, they're my crew, and my job was to lead them like I led young boys in Harvey's all those years ago. The best bit of the entire journey was actually teaching and inspiring them.'

As soon as we have finished the first course Marco asks, 'Do you still smoke? Do you want a fag?' so we dash outside to puff away under scaffolding in the rain and he gives me his jacket to keep warm. 'It's not bad sneaking for a fag outside, is it? Are you happy in life, Lynn? Despite your bereavement? I think the best you can do is accept it, like with my mum - the pain will never go. I'll always remember 20 February, the day she died, and 30 November, her birthday, so I always go very strange on those days - I always go to Brompton Oratory and light a candle and stay there for about an hour by myself. But I've learned to accept it, and my mum lives on through my children. I'm not saying life's easy - I have my complications - but it all contributes to this life we live.'

Back indoors for the main course, I ask whether doing Hell's Kitchen made him want to get back to cooking? 'No! I've been there, done that. I won my three stars, I did what I had to do, and you've got to move on. I wouldn't want to be in one room, 20 hours a day, 52 weeks a year, with four white walls and a stove. I think it stunts your growth as a human being. When I left the kitchen at 38, I was quite socially inept. I think I've developed more as a person in the past seven years than I did in all my years in the kitchen.'

But what's he been doing all this time? He has opened several restaurants and closed some of them, he has established a pasta chain called Frankie's with Frankie Dettori that seems to be doing quite well, and has just opened a new Marco's at Chelsea football ground. He has published his autobiography, White Slave, though he freely admits it was all written by his friend James Steen, 'But I did lots and lots of interviews with him and it's the most wonderful form of counselling ever, free of charge, and I was being paid for it!'

But even he admits that he has not been focused, like he used to be. 'To be quite honest, I did nothing in seven years really, apart from try to discover myself and understand myself as a person. I was unemployed and I'd lost all sense of direction in my life. I was 38 and I'd just had enough. Because I'd won my three stars at 33 and I felt, "Oh, is that it?" It was quite weird. If I'd been 48 like Albert Roux [when he won three stars] it's different, but at 33 - it was very young. When you start, you're always pushing, always chasing, wanting to do better and better, but once you get to that level, it becomes very systematic. And I just thought: I'm not happy. I thought that by winning three stars I would be happy, I thought I'd be accepted. But I was almost in a worse position. Because when you're a one-star chef, your mentors don't feel threatened by you; even when you're a two-star chef they don't, because they're still top of their tree and they think 'my boy Marco' - because remember, I was totally home-grown, I never went to France. And then when I won three stars, they'd all started to crumble, or got bored with the stove, and what they couldn't cope with was that Marco was now the boss in their world. And then I saw the knives come in behind me and I started getting disillusioned with my whole world. Because with all my failings, I'm a very loyal individual.'

This is not the impression one gets from his autobiography. In the past seven years Marco seems to have fallen out with everyone - with his protégé Gordon Ramsay most publicly, but also with his mentor Albert Roux who he used to say was 'like a father' to him; with Michael Winner who paid for his honeymoon; with Michael Caine who backed his restaurant Canteen; and with his youngest brother to whom he hasn't spoken for nine years. In White Slave, he recounts these fallings-out as if they were great moral victories, but they hardly resound to his credit. Take the famous incident at Heston Blumenthal's Fat Duck restaurant in Bray. He was having lunch there when he saw Gordon Ramsay also having lunch. He immediately summoned Blumenthal and told him to tell Ramsay to leave. Blumenthal was embarrassed; Gordon Ramsay was furious and called Marco a 'fat bastard'; the other customers were agog. Marco thinks he deserved a standing ovation. For what? For making a scene in a restaurant? Respect!

A few months ago he threatened to sue Gordon Ramsay over a chapter in Ramsay's autobiography in which he admitted stealing the reservations book from Aubergine - his own restaurant - and then blaming it on Marco. Ramsay told Bill Buford: 'It was my one stroke of genius, fucking someone over without his knowing that I was the one who did it.' Marco threatened to sue for malicious falsehood but says now that he didn't need to sue because he got the publishers to withdraw the chapter. But of course they're still not speaking. Were he and Ramsay ever friends? 'No. Gordon worked for me. I helped set up his first deal at Aubergine. I was always brought up in life, by my father, never to forget what people do for me - unfortunately some people have short memories.' Quite - rather like his own short memory à propos Albert Roux.

But the most serious of all the recent fallings-out has been with his wife Mati, mother of his three youngest children. Their relationship was always fiery. In 2003 she found texts on his mobile phone which she thought meant he was having an affair with a woman banker and sent a message to everyone on his mobile saying, 'Marco Pierre White has left his wife and three children for Robin Saunders'. A year or so later she called the police to their house and accused Marco of assault - he spent the night in the cells though she never pressed charges. Last summer she marched into Luciano's and fired a waitress, telling her, 'You are the second waitress my husband is fucking'. On another occasion, she went to Frankie's and publicly demanded a divorce. And, according to Marco, they are now divorced - 'I have my decree nisi' - though they are still living together. Isn't that a bit odd? 'My life has not been normal, Lynn!' So are they back together? 'I think in life, the more you force things, they break. You just let things happen.' But is there someone else in his life? 'Not to my knowledge. And, to be honest, I have no interest.' What? No interest in women? This must be a first. 'Not really. I have my children. I get so much love from my children. I love my family. I know what it's like to come from a broken world.' So why did they ever divorce in the first place? 'On the record but not for publication - I think my wife was just trying to get my attention. Trying to win my respect. And that's her right. It's very easy for Marco to go off and do this, do that, do whatever. I have all this freedom in the world - or I'm perceived to have this freedom - whereas my wife is a mother and it can be very difficult for a woman.'

He claims that he is now more mature and happier than he's ever been. 'I think my biography played a very big part in that - going down that road of self-discovery and reliving my life and questioning everything. I stepped into Hell's Kitchen because I finally felt comfortable with myself as a person. Seven-and-a-half years is a long time away from the stove. But I felt very confident in myself mentally. I felt I could do the job. And I know my industry is very happy that I stepped back into the ring.'

Everyone was happy to see him back in the ring. So why doesn't he stay there - not necessarily in a restaurant but at least on television, teaching people to cook? He was so good in his heyday. Instead he is flying madly round the world in the next few months opening new Frankie's restaurants in hellholes like Dubai, Abu Dhabi, Shanghai and planning 20 more Frankie's in the Caribbean. It sounds a nightmare: he says he enjoys it. He likes the fact that Frankie's is 'democratic', that families can eat there with their children. And he likes the people he is dealing with. 'Even in these superficial worlds, where one is an illusion, one is a building site, there are interesting people. And when I go to Jamaica for example, I love going to a jerk shack, I love buying fish off the locals - they all enrich my life and they all contribute to this multi-dimensional, multi-coloured tapestry that I live in. I've got to enjoy what I'm doing, otherwise there's no point in doing it.'

Oh maddening Marco. He seemed to have come back with Hell's Kitchen and now he's gone again. Such a loss.

· What do you think? Let us know on the blog

· Marco, Stamford Bridge, Fulham Road, London SW6; 020 7915 2929. www.marcorestaurant.co.uk