Food Critic Richard McComb enters the culinary court of Michel Roux Jr at his restaurant Le Gavroche.

I am eating the lunch that money cannot buy.

The food – platters of chicken, rabbit and livers, shredded courgette, a lightly-dressed salad, a bowl of peppered couscous – are good, as you would expect in a revered two-star Michelin restaurant that is habitually voted one of the nation’s best.

The wine is nothing short of stunning, possibly the best I have ever knocked back: a glorious 2003 Grands Echézeaux grand cru from Domaine de la Romanée-Conti in Burgundy. Robert Parker, the critic credited with having the best palate in the world of wine, rates the fleshy, jammy pinot at 96 points (out of 100).

But as is the way with all great meals, it is the company that really counts. To my left is Michel Roux Jr, chef extraordinaire and patron of Le Gavroche in Mayfair. He has invited me to break bread at the chef’s table before another whirlwind lunch service at the sumptuous basement dining room in Upper Brook Street, just off Park Lane.

It is the morning after the night before. Hours earlier, Claire Lara was crowned the winner of the BBC’s MasterChef: The Professionals, which Roux judges with uncompromising honesty. The MasterChef charabanc rolled into Birmingham this week, taking its place at the BBC Good Food Show Winter at the NEC. Roux’s kitchen enforcer, Monica Galetti, known for striking fear into the hearts of amateur cooks and professionals alike, is among the star turns.

She is at the table for lunch, too, demolishing a serving of livers that would fortify several dockworkers. Despite her tough TV demeanour, Roux’s senior sous chef, who is sitting next to head chef Rachel Humphrey, does smile, occasionally. Humphrey, on the other hand doesn’t, at least not before service. With the minutes ticking down until the first orders are called, she is so far in the zone I’m not sure she will ever come out.

Roux is relaxed but doesn’t eat much – just a nibble of green leaves, a few forkfuls of couscous. He’s a keep-fit nut, running marathons, and is as lithe as a whippet on a frosty morning.

“That’s not much protein,” I tell the chef. “I eat throughout the day,” says Roux. Not by my standards he doesn’t. When he arrived in the kitchen, the first thing he did was flip a mini brioche into his mouth and he had a sly dunk with some bread in the sauces of the chefs’ lunch as the plates stood at the pass. But that’s about it.

“I don’t want you to think we drink wine like this every day,” says Roux, offering me a glass of the Echézeaux. “It was left by a guest last night. Half a bottle.”

Didn’t they like it? “They enjoyed it but they’d had enough,” says Roux.

The wine is on Le Gavroche’s list for about £1,000. Chin chin.

We sit down to eat at 11.40am at one of the restaurant’s linen-draped round tables. Around us, all is immaculate: crystal, silver, rich flowers. The first diners arrive at midday. We leave the restaurant at 11.55am and in seconds all traces of our presence are removed.

I’ve been told the restaurant is full for lunch, between 60-70 diners, and ask Roux if that is always the case. He’s almost taken aback. “Yes,” he says, scooting off towards the kitchen furnace that lurks behind cool automatic glass doors.

Le Gavroche is booked for lunch several months in advance. On the day I visit, one party excitedly exchanges festive gifts. It is the nearest to Christmas they could get a table. It is November 3.

The day has started far earlier than this, of course. By the time I arrive in the kitchen at 9.30am, the 20-strong brigade of chefs has been toiling away from 8am. Five are shoe-horned into the tiny pastry section, working on classic tarte tatins, bread and petit fours. On the other side of the kitchen, the canapés are springing to life. In a central area, a chef is taking a blow torch to the skin of a dozen plump partridges while another preps the fish: cod, gurnard and red snapper. A young cook – most of them are young, frighteningly young – cleans and chops squid for a scallop dish.

And there she is, standing with her back to me, amid the well-ordered, steaming melee. Look on her works, ye mortals, and quake.

It’s Monica. With a very sharp knife. She is meticulously removing the sinew from a loin of venison with the cutting dexterity of a brain surgeon. The deep red flesh is destined for a dish of walnut gnocchi, butternut squash and chocolate sauce. Monica. Blood. Knife.

And she’s singing, like a schoolgirl – or serial killer.

I turn on the charm, introduce myself and tell Monica she looks slimmer, smaller, more petite, than she does on the telly. She really does. She’s almost cuddly.

“Are you saying I look fat on the TV?” she says. Oh, god. The knife.

Then her face cracks into a soft smile: “I wear higher heels on the telly, but Michel doesn’t want me to look taller than him.

I think she likes me, and this is good. Because it becomes clear during the next five hours, during which I observe lunch service, that Monica is the kitchen’s fulcrum. Sure, it is Roux’s philosophy – of great food, finesse and flavour – that permeates the place and Humphrey is clearly his anointed one at the pass, checking everything, re-plating if necessary, dribbling sauces on to fish and fowl with intuitive precision and tasting, always tasting.

But Monica is her master’s eyes and ears, and, to an extent, his voice, albeit it with a strong New Zealand twang.

Here’s how it goes. Before Roux arrives, the acrid smell of burning wafts through the kitchen. “What’s burning? What’s burning?” barks Monica, half inquisitive, half accusatory.

A chef has fumbled, spraying dried pasta over a flaming gas ring. Monica’s antennae are up. She zooms in. “Ryan! Are you on fire? Not that you’d know it ... Turn that ring OFF!”

Later, blood on her hands from dissecting the deer, she pulls up another young buck, telling him to tuck his necklace inside his T-shirt. “And make sure you have a shave before you come to work tomorrow,” she says.

During service, Monica is a multi-skilled culinary firefighter, whisking a gingerbread ice cream at one point, diving into the fish section at another. I swear she puts her naked palm on a searing hot grill. When she retracts her hand, it is unblemished. She’s like the Terminator.

A tableau: Monica is assisting, and reprimanding, a veg chef as he goes into meltdown during the heat of battle. The young cook is at breaking point, getting it in the ear from both Monica and Humphrey. He gestures as if to say something to Monica.

“Don’t even THINK of answering me back,” she says. “And stop looking at my arse.”

The kitchen falls quiet. It’s only for a nanosecond, but the point is made.

Minutes later, Monica slaps an arm around the young charge, who has picked up his game with the spinach. There is carrot as well as stick here.

Roux, whose own facial stubble escapes Monica’s wrath, had been in a pickle when he first arrived at 10.50am. A tube strike and a security alert meant he was very late, and he hates being late.

He had shook my hand, firmly, then jostled with Monica, pushing her. “You see, that’s where I get it from,” she says in mock horror. “He insults me. He feeds me bread and water.” And liver.

Roux then changed into his chef whites and prowled the kitchen briefly, his dark – they are almost black – hawk-like eyes scanning all sections.

During service, he assumes a roving position on the pass, opposite Humphrey, on the side the waiters come to for the extravagantly adorned trays of food. It’s an unusual arrangement and it must be a daunting prospect for Humphrey, to have her every move overseen by the grand chef, but she says she is used to it.

But what of Roux? Chefs are notorious control freaks. Roux also has a gilded culinary heritage to protect, Le Gavroche representing a dining dynasty dating back to 1967. Is is difficult for him to step back? “Yes,” he tells me as service peaks around 2pm. “But you have to delegate. I have complete faith in Rachel.”

Sometimes he can’t help himself. “Blimey, put a bit more sauce on there,” he says. It’s a rare intervention. This is undeniably Humphrey’s show.

It is very easy to be dismissive of TV cookery shows and Roux himself is no fan of the genre. MasterChef is about the only show he says he would put his name to.

“It fits me perfectly,” he says. “I don’t want to be on television for pure entertainment. There has to be something for the viewer to take home. It has to be inspirational and aspirational, which I definitely think MasterChef is.”

The standards keep improving, he says: “The young chefs that apply now realise what kudos this competition has. It is not just another one of these little television shows. No, this is for real. You can see it’s for real just by the expressions on their faces. They hang on every word I say.

“Whether they are eliminated in the first couple of rounds or whether they go to the final they feel they have learnt something and they have been enriched by the experience. That is very important for me and I wouldn’t do any television that doesn’t have that element to it.”

They are not empty words. At the end of a preparation area, Steve Groves, the winner of last year’s professional MasterChef, has popped in for a day’s experience. Twelve months ago, his winning menu showcased quail with morels, venison and a mille-feuille. Today, he is picking the leaves off herbs.

Groves says winning the TV cook-off opened so many doors for him. He has done stages, or kitchen shifts, at places such as Noma, recently voted the world’s best restaurant. Groves adds: “I have wanted to come here to Le Gavroche since I won the show.”

Across the narrow passageway is fellow 2009 finalist Dan Graham, an ex-agency cook. Graham has been working at Le Gavroche for a year. He joined two days after the final was broadcast and is now a chef de partie, overseeing the meat. He is searing a whole pheasant in a hot pan before roasting. As the skin gently crackles, Graham ladles in butter, which foams up. The heat is intense. Graham wouldn’t have it any other way. “The whole reason for me doing MasterChef was to slingshot myself into things like this,” he says, his enthusiasm bubbling like the butter in the pan.

I watch the final main orders go out, including Graham’s gorgeous-looking pheasant. It is off the menu, for a regular customer. All of it. And it comes with a truffle risotto.

It’s been a good service. The à la carte lobster mousse – £58 for a starter – sold out just after 1pm.

The prices, like the standards of cooking, are astronomical. But Le Gavroche is a different country – they do things differently here.

* The BBC Good Food Show Winter is at the NEC until November 28. The show features the MasterChef Experience in which contestants can dazzle judges John Torode and Gregg Wallace with their culinary skills. To get £2 off per ticket call 0844 581 1360 or visit www.bbcgoodfoodshow.com and quote LB1.