Walking into the Connaught Hotel in London is like taking a step back in time, retreating to some safer, cosier era when ladies wore hats, gentlemen wore suits and the likes of me were too busy polishing the floors and clambering up chimneys to cause any trouble. In the restaurant and the nearby Grill Room, it's the end of lunch service and only a few tables are occupied, all by older men. The atmosphere is clubby, exclusive, stuffy. There's a low hum of conversation, a genteel clink of polished silver on old china, waiters in tails exuding an air of quiet efficiency and old-fashioned servility. There's a menu that mixes English comfort food like braised oxtail and chicken and mushroom pie with hotel dishes such as sole meunière, plus the new dishes based on classic French cuisine that have made this hotel a benchmark in gastronomy for more than a quarter of a century. And there's maître chef Michel Bourdin, looking slightly awkward and out of place up here in his toque and cook's trousers, but visibly growing in stature as he leads me down from the faded grandeur of the lobby into the gleaming, modern kitchens that are his undisputed domain.

'You are now taking the royal entrance,' he tells me proudly as we descend the nondescript stairs. Apparently when the Queen Mum came to open the new kitchens in 1992, the Connaught refurbished the lift in her honour, but the Royals don't do lifts if they can be avoided.

The fact that both the Queen and Prince Charles have also visited his kitchens is of immense importance to Bourdin, an ardent royalist who sees it as a mark of respect not just to him, but to his profession in general. And nothing is more important to Michel Bourdin than the prestige of the chef. 'The Queen Mum told me my profession was an art,' he tells me later, 'and she knows what she's talking about. It's a way to express yourself. Some people do it through music and painting, I do it through cooking.'

The two dining rooms upstairs are small, dark, elaborately decorated. The kitchens below are clean, bright and seem to go on forever. More than 50 chefs work here to prepare the dishes served above, and absolutely everything is made from scratch. There is even a full-time butcher, preparing the cuts of meat from carcass.

'People call it the Rolls Royce of kitchens,' says Simon Crawshaw, who started his career as an apprentice here in 1987 and is now head chef at the Sloane Club in London. 'I don't think there's anywhere else left in London that does its own butchering. Now you just open a packet and put it on a tray. Fish the same - you buy it filleted, whereas at the Connaught they buy the whole fish and clean, scale and fillet it. The catering trade can't afford that kind of labour any more. We have to buy things in half-prepared.'

'As a chef of tradition, Michel Bourdin is probably unsurpassed in the modern culinary era,' adds Paul Heathcote, now head of a restaurant empire across the north-west of England and another Connaught graduate. 'There are very few traditional kitchens of that kind left in the world. I went there quite late in my culinary life, when I was 22, 23 years of age, and it was a real shock to find that there were 52 chefs in the kitchen, 13 people in a section. They made you go through every single process, and not cut any corners. It was a meticulously hard school, there's no question about it. But I learned an enormous amount there.' An affable, unassuming man, Bourdin enjoys such accolades, but he can also laugh at himself. He tells me he was born too short, pointing ruefully at his rotund belly: 'There is no room for my love pillow to spread out.' His office, just off the main kitchen area, is small but comfortable, its wood-panelled walls covered in framed diplomas and awards, photographs recording the royal visits and other mementoes of his long career as a chef.

'Look at me there,' he says, pointing wistfully to an old black-and-white picture of himself early on, during his nine years at Maxim's in Paris. 'Look how beautiful I was! The young playboy. You can't stay young all your life, but you do become wiser.'

In December, at the age of 58, Michel Bourdin is to retire from the Connaught after 26 years. Jerome Ponchelle, the Frenchman he has chosen and trained to be his successor, has been at the hotel for a total of eight years, off and on, the last three of them as executive chef. He is now 32, the age Bourdin was when he took over the kitchens, and his mentor feels it is time to hand over: 'He's got all my knowledge, but he's got one thing I don't have. He's young. There can't be two captains on the same ship. And I don t mind jumping.'

When Bourdin arrived at the Connaught in 1975, he was told to change nothing. And many of the dishes listed on the menu then are still there now. The kipper paté is still made with fish cured by J. Curtis Ltd, who began supplying the hotel in 1910. The recipe, however, is lighter, better, more suited to the times. Similarly, the steak and kidney pie is now made with best blade steak rather than chuck beef.

Slowly, quietly, Bourdin made his mark. When he arrived, the hotel's terrine came out of a tin. He replaced it with something more elaborate, but whenever Cary Grant came to stay, the can opener had to be retrieved. 'It took him a while to get used to the new style,' smiles the chef. He also recalls the day he sent out Sir Alec Guinness's favourite dish, poached haddock Monte Carlo, beautifully arranged on the plate. The actor sent it back, insisting on seeing the fish removed from the bone at his table. 'At the Connaught,' he said haughtily, 'I expect to be served.'

The hotel never gave way to new fads such as Nouvelle Cuisine. 'This,' says Bourdin, 'is why its cooking has never gone out of style. It is classic, like Chanel, Monet or Mozart. Not many people do that any more. That's why I've been so popular with Americans - even in France, they can't find a great French restaurant the way they expect it, so they have come to England to find it.'

Jerome Ponchelle will be only the sixth maître chef - all of them French - to work at the hotel since it opened in 1897. He will work alongside the sixth manager, who took over just four years ago. Bourdin insists that they, too, will make no radical changes. 'Jerome will evolve with the Connaught, but he will not change it. Which I think is very important. The Connaught is about continuity, and about change within continuity.' That may be true, but for many, Bourdin's departure will mark the end of an era.

Bourdin's training in food began, he says, soon after he was born. His grandmother was a cook, working for a wealthy baron in Paris who loved her food so much that he proposed marriage. She married a grocer instead and opened the Brasserie Bourdin, which still stands on the Rue de Temple in Paris. Michel's father worked there and the family lived above the business, so Michel grew up with the cooking of his grandmother's native Normandy.

'Even in the war we had a few hams and things hiding in the loft, so I've been used to good food since my childhood.' In his early teens, he was sent to spend his summers in Norwich, to improve his English while looking after the three children of a family called the Pastons. England in the 1950s was a culture shock - he loved eating with the family, but he found the English habit of leaving their youngsters outside the pub absurd, and the food was of course appalling. 'I was starving sometimes, because I was used to eating well. But I loved the fish and chips.'

By then, Michel's parents had sold the brasserie and opened a bar instead. They were always working, he says: 'They spent their lives making money, and they didn't have much time for me.' Michel had a half-brother, Guy, who was 15 years older. Guy's mother had abandoned him as a baby so he had been brought up by their grandmother, and Michel spent much of his time in Normandy with her and Guy. 'They were my real family.'

Guy Bourdin became an influential fashion photographer, his position at French Vogue in the 1970s rivalled only by Helmut Newton. Even though they had different mothers and very different temperaments, Guy and Michel shared a fierce perfectionism, an urge to create. 'We had parents, but we did not have parents,' muses Michel now. 'So maybe we both put our energy into something else. Artists have this problem, feelings that they can't express. I think my brother was upset to have been left by his mother when he was so young, which is why he was so difficult with women. He made their life hell - he wanted to punish women because his mother let him down. He revolutionised fashion photography, made it into an art. But he was mad! Oh la la! He was genuine in his art, but a difficult person to live with.'

One of the first commercial jobs Guy was offered involved expensive jewellery. He chose to shoot it draped over a penis. The picture was never published. 'This was the Fifties, can you imagine?' laughs Michel. 'Whoa, you can't do that! He did some very naughty photos, you know. Naughty, but beautiful. Even sex was not sex for him, it was photographic art.'

Guy was proud that his brother chose to be a chef, and when he was in London, he would come to eat at the Connaught, bringing his models and entourage with him. 'It was difficult for me, because I'd say to my manager, "My brother is coming, he will have a tie on, but I can't guarantee the rest". But he behaved.'

At the end of the Eighties, they talked about working together. Guy had never photographed food, but after watching his brother work, he came up with an idea. He would set Michel's creations in different environments, so his Chartreuse de Perdreau a l'Ancienne would be photographed by the Taj Mahal, the monument's dome echoing the shape of the pigeon dish. Similarly, his Croustade d'Oeufs de Caille Maintenon would be pictured floating on the Nile. It would have been spectacular, Michel smiles, a combination of their two art forms, but it was not to be. Before work on it began, Guy died of cancer in 1991.

Still, through his kitchens, Michel Bourdin has built himself a different kind of family. When he arrived in 1975, London was a gastronomic desert. There were only a few chefs of any note working in the capital - the Roux brothers, Anton Mosimann, Peter Kromberg. They formed an organisation called the Club du Neuf to try and encourage good practice in kitchens and to train a new generation of British chefs. And Bourdin took to it with a passion, virtually writing the manual for the modern kitchen apprenticeship. He offered the greatest foundation for any young chef in this country, says Paul Heathcote. There may be people with more gloried records in turning out Michelin-starred chefs, but there is nobody that has turned out more thoroughly professional and disciplined chefs.

'Developing young chefs, that's his passion,' adds Martin Green, who worked with Bourdin for 11 years and now heads the kitchens at White's Club in St James's. 'That and truffles. He's crazy about the profession, about improving the profession - he always has so many ideas.'

Bourdin says it takes 15 years to make a chef, providing he gets them at the age of 16, before they know everything and lack the patience to learn. He always interviews the parents too: 'If they are committed I know I'll keep the young man longer.'

He's looking for a certain sparkle in the eye, a passion for food. 'I tell them that if they wanted to be a musician, and I asked if they liked music and they said, "I'm not too sure", they'd have no chance. It's the same if you want to be a cuisinier. If you don't love your food, do something else.'

They do five years in his kitchens - three years of apprenticeship, working in each section of the kitchen in turn, then two more years in which they revisit the sections again, taking on more responsibility. After that, he'll fix them a job in a good kitchen elsewhere. Some come back later, to work with him at a higher level; most go on to be head chefs in their own right.

'By their early thirties, they'll be a chef, a real chef, who doesn't have to copy anyone to cook. After 15 years of basic, you should be able to play real music. You don't need a book.'

Seventeen years ago, he formed the Club des Amis, an annual dinner reunion for his protégés: it was at the Sloane Club this year, Claridges last, with over 100 of them at the table. He knows where all of them are now, keeps their names and contact numbers in a big book in his desk. He has chefs in most of the great British restaurants, and all across Europe. One runs the Orient Express in Singapore; another became a businessman and is now in charge of Swissair. He has chefs in Canada and the USA, 10 in Australia, one in China.

'They've all done very well,' he says admiringly. 'Strong people. The first chef who left me as an apprentice, he went on to run a two-star Michelin hotel in France. Because he knew everything.' 'No one who's worked with him will say anything bad about him,' says Martin Green (correctly, as it happens). 'Even after I left to open St David's Hotel in Cardiff, I was on the phone to Michel every few weeks. He's a very emotional person and he likes to be a father figure to all of his team. He really cares about them.'

Culinary history is important to Bourdin, a thorough knowledge of the basic principles of cooking an essential. 'In many restaurants now,' he says, 'they make the presentation before the taste. Sometimes it looks good, but it doesn't taste good. They don't braise, they don't roast, they don't grill. They don't even know that a duck is not just a suprême, that it can be cooked on the bone.'

He refers often to the long gastronomic links between Britain and France, and especially of the great partnership of the Swiss hotel manager César Ritz and the French chef Auguste Escoffier, who revolutionised hotels - and hotel cooking. Escoffier came to London with Ritz in 1890 and stayed for 30 years, cooking first at the Savoy and then the Carlton where his lavish meals made French cuisine famous worldwide.

Escoffier's spirit lives on in the Connaught's kitchens. Posters of him adorn the walls, and the restaurant's menu proudly declares 'we have maintained the style of menu designed by Auguste Escoffier, circa 1880'. After he retires, it is Bourdin's dream to see the hotel's two dining rooms - which have always shared the same menu - given separate identities. The restaurant would still serve the traditional British food and hotel specialities, but the Grill Room would offer more innovative, Michelin-style cuisine, becoming the Escoffier Grill to preserve the identity of the two men who created grand hotelry in the world, using Britain as a base.

For him, cooking reached a peak during the time of Escoffier - from 1880 to the start of World War I, and then again between the wars. Afterwards, gastronomy lost its way until the Sixties in France, and even later in England. 'By then a lot had been lost,' he mourns. The credibility and the knowledge of the chef. True, there is now huge media interest, but when most women cooked, children would inherit recipes and skills from their mothers, their grandmothers. Regional cooking had real meaning then, and chefs worked in restaurants and private homes where money was no object.

He's nostalgic for a time when people would dress up and use the restaurant as a stage, a setting for a night's entertainment. Now they eat out for convenience, then rush off elsewhere. As for young chefs - 'they all want to be Jamie Oliver'. He has nothing against Oliver. 'No one who encourages an interest in food can be bad. But when I've got mothers ringing me to say my daughter or son wants to be a TV chef, I say, "Madame, you should send her or him to drama college, not a kitchen".' Youngsters come to him now thinking that they'll make a million. 'But cooking is not that. Cooking is a long march that never ends. You keep learning. It's not an easy subject.'

Bourdin founded a British branch of France's Academy of Culinary Arts in 1980, and more recently managed to persuade Prince Charles to become its patron. He dreams of eventually making it a Royal Academy, with a status equal to the Royal Academies of Art and Music. If astronomy can be recognised in this way, he argues passionately, then gastronomy should be. 'We're more important than the discovery of a new star in the sky! You don't give a damn about a new star, but you like to have your breakfast, dinner and supper. And you want tourism and employment.'

Bourdin got his first Michelin star in 1975, his second two years later - for both of the hotel's restaurants, an achievement then unrivalled in the world. But in 1990, one star was taken away. Bourdin says the judges were confused by a menu that included, alongside his own innovations, traditional British lunches and the dishes expected of international hotels - omelettes, soups, smoked salmon. How can he be compared to establishments like Le Gavroche, he says, when he serves Irish stew? 'Not very clever, is it? But it's good. And people love it. The Connaught was born before me, and I have to look after my customers first. You know what happened the year they took me to one star? We did 20,000 more covers. Because there was an outcry.'

Afterwards, Bourdin and the hotel manager went on a grand tour of three-star Michelin establishments in France, covering 12 restaurants in 15 days. By the end, says the chef, 'I couldn't take any more of it! I was sick of it.' When he asked in one restaurant for a simple soup to soothe his stomach, he was told they could not serve it. We had to have cuisine Michelin. I found it odd, that you're not allowed to have a potage when you're sick in your stomach. It's the price you pay. So after we'd witnessed that, my boss said, "Michel, customer first".'

'He's a man that could have easily had two, three Michelin stars, but he sacrificed those high accolades because he felt what he was doing with his team - the training for the future - was more important,' says Giles Thompson, now head chef at the Ritz and another Connaught veteran. 'Whether it's understood now or not, his heritage will be looked back on and drawn upon if we are to maintain gastronomy at the highest level. He's sacrificed a lot for it. The dignity that he's brought to the profession is paramount. He's given back so much.'

Before I leave, Bourdin shows me his truffle locker. The season is just about to start, and so there are only a precious few of last season's dark, vacuum-packed treasures left. A young chef is preparing that day's ration, and lets me sniff the rich, earthy shavings collected in his bowl. It's a heady aroma. Last year good truffles cost around £600 a kilo, and the Connaught's kitchen used over 180 kilos.When it is full, at the end of the season early next year, the contents of this unspectacular cold store are probably more valuable than anything in the hotel's safe.

Bourdin says he doesn't know whether his famous truffle menu - a seven-course meal in which everything from the opening cocktail to the final dessert contains the precious fungi - will continue after his retirement. Indeed, he doesn't know how much longer many restaurants will be able to afford to serve them at all. He also shows me the chef's library. There was a time when it would be considered bad form for a chef to be seen by the customers. Now gourmands will pay to spend the day with Bourdin, helping to prepare a special menu which they then enjoy with their guests in the library, where recipe books line the walls and a wooden plaque is engraved with the names of the Connaught's long-term suppliers. He points out that a chef is only ever as good as his ingredients.

It's hard to imagine any chef starting a job in London now and staying 26 years. Recently, the big hotels have tended to buy in talent rather than developing it themselves, bringing in established brands (Nobu at the Metropolitan, Spoon at the Sanderson), or chefs who are already stars (Gordon Ramsay at Claridges). Marco Pierre White, one of the finest chefs of his generation, has retired to become a restaurateur before even reaching middle age, while Gordon Ramsay's interests are expanding at such a rate that he can no longer be in the kitchen every day. The role of the chef is changing, mostly for the better, although many in the trade wonder where the next generation is to receive the kind of thorough training it needs if this progression is to continue.

Meanwhile, the commercial pressures of the twenty-first century are already creeping into the Connaught's closed world. After my first meeting with Bourdin, the hotel's PR indicated that his Escoffier Grill may remain a dream. There are few Americans booking into the Connaught now, and like all luxury hotels it faces a period of uncertainty.

Londoners, too, can now find the kind of simple, classic French cooking that has long been the Connaught's specialty served up far more accessibly in modern restaurants like Marco Pierre White's Drones. 'When I was at the Connaught it was real old school, people had been going there for years and didn't want it touched,' says Martin Green. 'Now those people are dying off and younger people want something a bit more trendy. But there's room for both - the Connaught will always be successful at what it does because it will always have the best ingredients, and some of the best chefs. You pay a price, but you also know you're not going to come away disappointed.'

As for Bourdin, he will be returning to France, to his house in Grasse and his wife of 40 years. But he is hardly planning a restful retirement. 'Like an old star, I'll do some comebacks,' he jokes, promising to return to the Connaught occasionally, bringing along some of his famed French colleagues. He'll still be active in his beloved Academy of Culinary Arts. He's also planning a book about his life and the dishes he created for the likes of Maria Callas, David Niven, Princess Grace and Humphrey Bogart that he hopes to see published in 2003, for the centenary of Escoffier's most famous work, Le Guide Culinière. But first, he has a more pressing engagement. 'I am going to dress as Santa Claus for my little granddaughter,' he says. 'That's my first priority.'

'It's a worry who will take that mantle now,' says Paul Heathcote. 'I don't think there is anyone, really. Now that he's left, the commercial world will change the Connaught - that's inevitable. It is the end of an era, and the professional kitchen will sorely miss Michel Bourdin.'