Day in the life of London's smartest cafe

Apparently this 28-year-old has a shop on Mount Street and hosted a party for her friend, Kate Moss, in Bali this summer. (She had porridge and honey which is very fashionable apparently, as is the carrot and ginger juice and the boiled egg with soldiers.) It's all reasonable, too. The full English costs £12.50. It's £28 at Claridge's.

"Business, beauty, brains and bull-shitters are all under one roof here," says Greig. It is not clear which category he comes under. "Like the Coliseum, no one has a bad view."

Sir David Frost is eating bacon and eggs with a friend. I table hop. "So, do you like Frost/Nixon?" I ask him of Peter Morgan's play, based on his 1977 landmark interview with President Nixon (which took the Editor's Award at this week's Evening Standard Theatre Awards). "It's a good play," he says, looking spry. "And they've much right."

I ask if it's true that Nixon called him the night before the Watergate scandal broke, as the play suggests. "That may not have happened," he smiles, "but I'm perfectly happy for it to be included." And off he skips, past a table where Damien Hirst has "dropped in for some porridge". "Damien comes for breakfast," says a waiter. "And Lucian Freud is often here for dinner."

Others breakfasting include Ben Elliot, who had popped in before flying off to Dublin to launch his burgeoning Quintessentially concierge service there. "This place is magnificent because of the way Chris and Jeremy look after the guests," he says (guaranteeing himself a table for the foreseeable future).

I realise throughout the day that King and Corbin have reached a curious place in their role as owners. Their guests are equally happy sucking up to them as they are to their guests.

Elliot sits with man-about-town Piers Adam, who has just opened Mahiki around the corner on Dover Street. It's the hottest club in town right now, I'm told. "I use this place like an office," says Adam. "I'm always in here." Two hundred and seventy people had breakfast on the day I was there.

By 10am things thin out and I move into a salon at the front of the restaurant for a coffee with Fay Maschler, who I have asked to join me to tell me why, as a restaurant, The Wolseley has had such an effect on London.

"It's both supremely elegant - a case of where details such as linen, glassware, coffee service, cake stands impinge quietly but potently - and accessible," she says as we eat a rather average fruit salad. You can buy said glassware. "The stated aim of recreating a Middle European Grand Cafe is achieved. You spot people who know how to get the best out of restaurants visibly responding to what this unusually egalitarian establishment offers."

"Egalitarian?" I splutter. Surely not. But according to MD Robert Holland 30 per cent of all trade comes from people like me, walking in off the street. "We keep back tables on a first come, first served basis," says Holland, who reveals that a staff of 130 waiters, chefs, doormen, baristas, washer-uppers and managers are needed and that the only downtime is between 2am, when the last staff leave, and 3am when the pastry chefs start baking. Oh, and they use four tonnes of coffee a year, and 8,000 eggs a week.

In his light grey three-piece suit, King tilts his towering frame towards Sir Peter Hall, who is having lunch to celebrate the fine notices for Amy's View, which he has directed and stars Felicity Kendal. King, who worked at Joe Allen's in the early Eighties (Corbin was at Langan's), has a deference and professional charm that is borderline eerie.

"He's a brilliant restaurateur but I wouldn't want to work for him," says a Wolseley regular who won't be named because they want to stay a regular. They are taskmasters, I gather, but to make this place run as smoothly as it does - the service is remarkably unflustered and accurate - they need to be.

I ask King why he thinks The Wolseley has made such an impact. "We always wondered why London couldn't have an all-day brasserie. We wanted to give people what they want, when they want and how they want.

"I love seeing a row of tables where one is having English tea, another fruits de mer, another chicken soup and another steak frites. That's when I know we've achieved what we wanted. It's a democratic restaurant."

I have lunch with television executive Zad Rogers, son of architect Sir Richard, who along with his business partner, Kirsty Wark, recently sold their production-company IWC to RDF. I have a Bloody Mary - it's been a long morning - plus snails and confit of duck. It's all excellent and just as good as Brasserie Lipp in Paris or Balthazar in New York, two establishments which are influences.

Dawn French is having lunch with some friends on the eve of her new BBC show Jam and Jerusalem. There is a ripe moment when Sir Peter Hall comes to give her a kiss on the way out. His stately frame is unable to stoop while she struggles to raise herself up (it turned out later that she had pulled a muscle). They compromise with a hand stroke.

On the table next to me sit a couple in their fifties who look as if they'd be handy at a village fete. They order a late lunch of Cornish crab, croque monsieur and champagne. "It just looked so lovely from outside so we came in," they tell me. "We're from Stevenage. Do you know it?" They'd never heard of The Wolseley and why should they? "We are in town to do some Christmas shopping."

Between lunch and afternoon tea the place never empties. I had the best cheesecake I have ever eaten but other couples come in for Matjes herrings with beetroot or warm chicken soup, a group of five chit-chatty housewives gossip over finger cakes and in the corner, alone, Ralph Fiennes orders a burger and talks to himself. He is learning lines for Beckett's play First Love in which he will star during the Sydney Festival. He likes coming here because he is left alone, he can eat what he wants at any time of day and he feels "part of London".

I am into my 13th hour when the place moves into dinner mode. There are lots of families with young children scoffing fries and suckling pig before the theatre.

My guests for dinner are the actor Johnny Standing and his journalist wife Sarah, both regulars. "It manages to turn any small event into a grand occasion," says Sarah. There could be few smaller occasions than dinner with me but the place was throbbing. Beautiful girls flit about and marvellous Nicky Haslam is having dinner with Sir Reresby Sitwell (a lesser-spotted sighting) while Stuart Rose works the room soaking up praise for M&S profits.

And so the night goes on. People are still ordering dinner at midnight. At 12.43am, a kindly Mr Holland gives me a glass of 1975 Armagnac to celebrate. "You've been here longer than any of my staff," he says.