Simon Hopkinson is a god to food-lovers but, like all the best gods, remains invisible most of the time. He used to write a cookery column for the Independent but gave that up four years ago saying he'd run out of things to say. He occasionally fills in for other columnists or reviewers (he filled in for our Jay Rayner the other week) but says he would hate to do it as a regular gig. He won't do television because he is shy. He used to have his own restaurant, Bibendum, but gave that up in tears, literally, in 1994, and says he'll never work in restaurants again. Is it because he's lazy? No, he says, more because he's a coward. He is modest to a fault.

Two years ago, just as his friends were beginning to worry that he'd gone into premature retirement (he was only 51) he was suddenly 'rediscovered'. Waitrose Food Magazine asked a panel of chefs and cookery writers to vote for the most useful cookery book of all time and Simon Hopkinson's Roast Chicken and Other Stories, first published in 1994, emerged as the clear winner, beating even Elizabeth David. The book had sold 800 copies in the whole of the previous year, but after the Waitrose vote it started selling 900 copies a day, and briefly supplanted Harry Potter at the top of the bestseller lists. Suddenly, unwillingly, he was thrust into the limelight again. And now he is making another of his rare appearances because he is publishing a new book, Week In, Week Out, a selection of his recipes with photographs by Jason Lowe - typically, he says he wanted to publish it to preserve the photographs, rather than his recipes.

I can't remember when I've looked forward to an interview more. Hoppy, as everyone calls him, emailed to ask if I'd 'mind' coming to his flat for lunch and did I like grouse? Did I like grouse? And perhaps a spot of claret? Mm, mm, mm - I was salivating all over my laptop. The only thing I felt I ought to warn him was that I smoked and would have to pop out for a fag from time to time. No problem, he emailed back, he smokes like a chimney himself. Man of my dreams - a smoking chef! He says there are loads of them - it's a complete myth that smoking ruins your palate - and sure enough I saw several famous chefs at the launch party for his book, puffing away on the pavement outside Bibendum.

Hoppy's flat is in an unpromising street behind Olympia, but the sitting room is lovely, looking out over leafy gardens and hung wall to ceiling with excellent prints, including several by his friend Howard Hodgkin who painted the cover for Second Helpings of Roast Chicken. The room is crammed with interesting things - a row of antique pâté pots, a collection of model aubergines - with two beautiful Siamese cats strolling elegantly among the clutter. The only clear space is the huge dining table by the window overlooking a windowbox herb garden of basil, mint and chives.

So far, so lovely - but then we come to the kitchen. Small, thin, old-fashioned, with an ancient clothes dryer hanging from the ceiling, it would never make it to the pages of a style magazine. The stove is an elderly Britannia, gas on top, electric beneath, hung all around with pans and ladles, and his store cupboard is a black hole containing some of his secret vices - tins of baked beans and butter beans, Fray Bentos steak and kidney pies and Sarson's malt vinegar. His spices and stock cubes are all higgledy-piggledy on open shelves, with rows of pans and copper pans above. It's not exactly a dream kitchen, I tell him. 'No? But I think it's very nice. Small is good - if you have a huge kitchen you spend all your time walking up and down.'

He shows me the grouse we are going to eat neatly sitting on pats of butter in a roasting pan, untrussed but with their legs pinned together with cocktail sticks. He deplores the standard butcher's habit of trussing and putting bacon on top because he says the bacon spoils the flavour and trussing means you get a raw patch between breast and thigh. He sprays the birds with olive oil but only just enough to make the seasoning stick. He also shows me two unprepared grouse, still with their feathered wings and heads on, and asks me to mention that he buys them from Allens of Mayfair, the best game butcher in town. He buys them 'long leg' which means with the guts still in, and you can test the age of the grouse by feeling the bendiness of the claws - the bendier, the younger. 'Have a smell,' he offers. 'The guts actually preserve the meat - that's why hanging works. Obviously you can't keep them forever and when people say they hang pheasants for three weeks till they're green and crawling with maggots, that's not nice! But a good chicken can be hung for a week in a cool place with its guts in because the bird is intact, it's all sealed in. But once you've taken the guts out, that's when putrefaction begins.' He shows me the bread sauce and game crumbs and gravy he made earlier and then shocks me by saying, 'They're all for you - I'm on a diet.'

This is terrible news, but he tells me not to go on about it, and anyway it's a diet - protein and citrus fruits, as taught him by Jonathan Meades - that allows him to eat grouse, just not the trimmings. He has to diet periodically because he can't eat in moderation and, 'I hate myself when I get too fat, when I can't do my shoelaces up or when I roll over in bed and my tummy takes a while to come round. It's just about being happier.' He doesn't actually look fat at all, just rotund, but he says he'll feel better when he's down to 13 stone.

He puts the grouse on to cook for 20 minutes (then they have to rest for 20 minutes) and produces a delicious half bottle of pink champagne, Billecart Salmon, to drink while we chat. From his books, I was expecting him to be quite curmudgeonly (he gets so cross with people who are too lazy to skin new potatoes or to cut the sharp ends off beans, ie people like me) but actually he turns out to be a pussycat. Tom Parker Bowles had told me on no account to get him started on Gordon Ramsay because he would rant on for hours, but apart from saying that he preferred the old Connaught before it got Gordoned he was quite restrained, though he did say he hated programmes like Hell's Kitchen where everyone screams and shouts. He has a lot of time for Delia and says he always used her Yorkshire pudding and steak and kidney pudding recipes at Bibendum 'because they are correct' and he is fond of Jamie Oliver despite him once saying that five-spice was an Indian condiment - it is Chinese. And of course he admires Nigel Slater. But ask him about other telly chefs and he switches off - 'I'm sure they're all lovely - I just never watch them'.

He is happiest talking about his childhood and especially his memories of food. He was born in Bury, Lancashire, in 1954, the younger of two boys. His father was a dentist, his mother a schoolteacher, and they had a big house with apple trees in the garden and - most important - an Aga in the kitchen. In his cookbook, he waxes lyrical about his mother's meat and potato pies, his father's steaks, the 'lambs fries' (testicles) that his father would leave in the Aga overnight for breakfast, the potato cakes his mother made for tea on Sundays, eaten out of a Pyrex bowl in front of the fire. 'Mum did the everyday things but they were good things - braised steak, cod with parsley sauce, rabbit pie, hotpot, queen of puddings, crumbles. Dad did more experimental things - I remember we went camping in the Costa Brava in the early 1960s and he brought back a paella dish because he wanted to make paella when we got home. And I still have Dad's paperback copy of EP Veeraswamy's Indian Cookery - he would go into Manchester to buy all the spices and make very good curries.' Were they a fat family, with all this eating? 'No! I think people ate more in those days because we didn't have central heating. We just ate well.'

He started cooking when he was 12 or 13 - his speciality was curried eggs for his parents' dinner parties. One holiday, his parents took him to a wonderful restaurant in Honfleur and he resolved there and then to become a cook. Luckily for him, there was an excellent French restaurant, La Normandie, in Birtle about five miles from Bury so he worked there in the school holidays and then signed on as an apprentice when he left school at 16. 'The first time I went my mother drove me there and I was saying Go! Go! and Yves Champeau took the mickey for weeks afterwards, saying "Is Mummy coming to collect you?" Awful. But he was a terrific teacher.' The Normandie was one of the top 16 restaurants in the Good Food Guide and nearly all the staff were French so he had a thorough grounding in French cuisine, but he wishes in retrospect he'd had the courage to train in France - 'I was too scared to do that. I'm not very brave. I wish I had done though. But I learned a lot at the Normandie.' Roast Chicken and Other Stories is dedicated to the memory of Yves Champeau.

From the Normandie, he went to a restaurant in Cheshire, which sent him on to a hotel they owned in St David's, Pembrokeshire. His parents came to visit him and liked Wales so much they moved there. Hoppy then set up his own little restaurant, The Shed near Fishguard, which was just five tables and himself in the kitchen - and at 21 became the youngest chef to win an Egon Ronay star. So then he thought he'd like to be an Egon Ronay inspector and spent two-and-a-half happy years eating lunch and dinner in restaurants five days a week. 'I thought it was the best job ever, being the greedy boy I was. But I did go over 15 stone!' He was never intimidated by restaurants, however grand. He remembers, even at 17 sending the mayonnaise back at L'Epicure, in Soho, because it was split. He is shy in many ways, but not when it comes to food.

In his late twenties he worked as private chef to a City magnate called Christopher Selmes in Cheyne Walk, Chelsea. 'It was a lovely three years, I had an absolute free rein, I could cook anything I wanted. And it was near the Fulham Road which in those days had a great butcher, a great greengrocer and Luigi, the great Italian deli that is still there, and I'd walk up there and shop every day. I rarely had to cook for more than two or three at lunch, a few more in the evening, occasionally for 10, and I served the food - there wasn't a butler. The Roux brothers have said many times that private cooking is a very good opportunity to experiment and find your own way and I agree - I'd do it again, absolutely.'

In 1983, not yet 30, he was offered his own restaurant, backed by the Kennedy Brookes chain. It was Hilaire, in west London, and opened without any fanfare, but soon Fay Maschler gave it a rave review and people like Elizabeth David started turning up. Terence Conran came at least once a week. Then in 1987 Conran announced that he and Paul Hamlyn had bought the old Michelin building and wanted to start a restaurant and would Hoppy be chef? Again, great reviews, huge plaudits, Elizabeth David coming up in the goods lift for meals, but he found the responsibility of a big kitchen 'torturous, worrying, dispiriting' and in November 1994 broke down in the middle of dinner and could not stop crying.

He says that even before the breakdown, he'd decided to stop cooking at the end of the year because 'I've always been a cook rather than a chef - chef means chief - and I just wasn't happy in the job. Then that night in November I completely lost it, and had to go out in the middle of service and have a big cry. Everyone came at the same time - we did about 80 covers in an hour and a half - and there were two big tables, one of which was Alain Ducasse, who wanted to come in the kitchen but I said no, even though he said the steamed ginger pudding was one of the best things he'd ever eaten. And I had a very irritating head waiter at the time who just pushed me over the edge. And when that sort of thing happens, I just go under.' He didn't throw knives? 'No, thank God, I've never thrown anything in my life. But I just sort of crumple, I collapse.' He managed to keep going at Bibendum till New Year, as promised, but then renounced the world of restaurants forever. 'I absolutely don't want to go back in the kitchen, ever.'

However, he is still a partner in Bibendum and drops in there once a week to talk to the chef. The income from Bibendum means he doesn't have to work for a living and although he is always 'making notes' towards another cookbook he doesn't seem to feel any great sense of haste. 'I'm not unbusy,' he claims, 'but I'm not overworked.' He swims most mornings, and then wanders round the shops seeing what looks good, and of course he cooks a lot - bacon and eggs for his breakfast, maybe a lamb cutlet with béarnaise sauce and new potatoes for lunch. He throws occasional big lunch parties for friends including Howard Hodgkin, Stephen Fry, Fay Maschler, Julian Barnes, Albert Finney, and Helen Worth, the actress who plays Gail in Coronation Street, a long-time friend who brings him black pudding from Bury market. At weekends, he often stays with friends in the country and takes over their kitchens - 'I love cooking in other people's houses, I feel very relaxed.' Jay Rayner describes him as a 'compulsive' cook who can never not be cooking.

He lives alone, which is the way he likes it. 'I think even if I was straight I would still be an old-fashioned bachelor. I did have two relationships a while ago but it was me that finished them - I'm too set in my ways. I am incredibly happy on my own, I'm very good at being content, I'm never bored, I can go on holidays on my own and love it. That's not to say I haven't got some very good friends who I am fond of and see a lot of, but I'm good at being just me really.'

He is perfectly happy going to restaurants alone and often takes himself to Paris for the day to eat at an old favourite like the Brasserie Lipp. 'I love the efficiency of it and the fact that they've all been there forever. I'll take the papers to read but end up not reading anything because I'm just enjoying the atmosphere so much. Or there might be a handsome waiter! But just a romantic thing in my head - the unattainable object of desire.' He likes going to the same tried and trusted restaurants; he can't understand the modern frenzy for going to new restaurants every week. He never wants to waste a lunch or dinner by eating somewhere that might turn out to be disappointing - life's too short, he reckons, to eat a bad meal, ever. The Gavroche, he says, used to have an old man who ate there alone every day and 'I can't think of anything nicer honestly - what a lovely retirement! Everything about going to a restaurant is more enjoyable if you know the place very well.'

But nowadays he doesn't go out to restaurants much, partly because of the smoking ban but also because 'I want simpler and simpler food. I went recently to Paris with a chum who wanted to go to a three-star, which we did, and it was very very good, but it was incredibly expensive and I thought I just don't want to go to these restaurants any more, I really don't. Is it growing up? Or growing out of it? I don't know.'

He is irritated by food fashions - he says there's too much rocket about these days and not enough lettuce, too much shaved parmesan instead of grated, too much extra virgin olive oil instead of butter and too much jus instead of gravy. He hates 'seared' things, especially tuna which he prefers raw, and 'smearings' and 'constructions': he thinks food should look like what it is, not pictures on a plate. He also objects to food misnomers - 'veloutés that aren't really veloutés and menus that say crispy for crisp. I'm a bit pedantic, or very pedantic really. I'm Mr Annoyed of Hammersmith.'

At this point he suddenly remembers the grouse, and dashes to switch the oven off, while he serves a cold starter - fabulous beetroot jelly which he says 'looks a bit cheffy, but is actually very simple - consommé made from good chicken stock with a bit of jellied pig's trotter, flavoured with beetroot, chilled and served with sour cream and chives on top.' It is so delicious I want to go on eating it all afternoon, but he says he will give me some to take home, and then he opens and decants a delicious Pauillac, Chateau Pichon Lalande 1975, and produces the grouse. He serves it with bread sauce, game crumbs on top 'to give a nice contrast' and gravy. Then watercress to sop up the gravy - it is total heaven.

For pudding, he produces a delicious white coffee ice, made from an Elizabeth David recipe. He became friends with her towards the end of her life, and of course admired her books, but the writer who really influenced him, he says was Richard Olney, author of the French Menu Cookbook and Simple French Food. 'He had more technique I think, but he was difficult. Of course Elizabeth David wasn't necessarily easy. Perfectionism, you know, means getting things right. That's my big thing - I want to get things right. It means you can't be easy-going.'

The odd thing is that, to meet, he seems very easy-going. I only got one glimpse of temper when I asked if his parents had wanted him to go into a profession and he said sharply, 'You mean cooking isn't a profession?' But otherwise Mr Annoyed of Hammersmith was nowhere to be seen - I suspect he only ever comes out over questions of food. But you feel, with Hoppy, that food is his most eloquent form of communication. If he likes you he gives you food - he once gave Jay Rayner a Tupperware box of tripe stew, which is not a present most people would thrill to but Jay took it as a great honour. I got a little Tupperware pot of the beetroot consommé to take home which I treasured and doled out, spoonful by spoonful, to my loved ones. Food as love, food as balm, food as consolation: that is what Hoppy is all about.

· Simon Hopkinson's Week In Week Out is published by Quadrille, £20. To order a copy for £18 with free UK p&p go to observer.co.uk/bookshop or call 0870 836 0885