When I’m told Nigella Lawson is happy to receive me in her kitchen, I anticipate a shifty poke around the YBA-spattered Belgravia mansion she shares with Charles Saatchi. Alas, no, “Nigella’s kitchen” turns out to be the premises where she is filming her new cookery series on an industrial estate off London’s roaring South Circular.

Yet behind the door of the anonymous unit, among property developers and software companies, fairy lights soften the concrete beams, a book shelf is crammed with Roald Dahl as well as Claudia Roden, there is a voluptuous pink sofa, glitter ball, tea-lights, pretty liqueur bottles, and the walls are covered in snaps of and artwork by Nigella’s children who hold their sleepover parties here. “The vibe is Barbie goes to Battersea!” she says as she gleefully shows me around.

This is the headquarters of that strangest commodity, the living brand:

equal parts stage set, laboratory and home. Everything we see Nigella bought herself, mostly on late-night eBay frenzies (she doesn’t compete in auctions, just slams in a high top bid). There’s her kitchen with a meat-locker-sized fridge and her pantry. Upstairs is a second kitchen and beyond that what she calls “my she-shed”, her rhubarb-pink inner sanctum containing an immense Annie Leibovitz portrait of Nigella in a ballgown with her babies. There are stacks of her trademark jewel-coloured cashmere cardigans and a framed photo of a younger, rather rakish and sexy Charles Saatchi.

The appeal of her first programme, Nigella Bites, in the late Nineties was not so much the recipes as the lifestyle it evoked, shot as it was in Lawson’s own house on West London’s insalubrious Goldhawk Road. The kitchen was chic yet chaotic: her son Bruno (now 11) iced biscuits, friends laughed over supper, and amid all this warmth and life was the melancholy sub-plot of John Diamond, Nigella’s first husband and long-standing columnist of this magazine, thin and silent, opening a bottle of champagne, unable, because of the throat cancer that soon ended his life, to share in the feast.

But those who first contrive to bring cameras into their lives later yearn to keep them out. Besides, Nigella has a new husband now and one doubts Saatchi, who eschews the public gaze so absolutely he never attends his own parties, would want a film crew tramping past his Emins and Hirsts, or a cameo role deglazing a pan. Moreover Eaton Square, with its library, immense rooms, staff and embassy grandeur, might alienate the greater cooking public. So Nigella has created a facsimile of her old, more modest household. She loves her home kitchen – Thirties-style, cream with dark wood – but felt obliged to design it in keeping with the house. “Here,” she says, “is more my untrammelled style. Mimi [her 13-year-old daughter Cosima] says it reminds her of Goldhawk Road. She calls it Mummy’s dolls-house.” Very Marie Antoinette, I jest, and Nigella shoots me a look.

Lawson has a dazzling range of conversational tone, flicking from imperious to sisterly, candid to bossily maternal: “Would you,” she asks as I prepare to leave, “like another wee-wee before you go?” She has a lively and acute, teasing yet unconfrontational intelligence: the mind most men would think perfect in a wife. Her lascivious, spoon-sucking TV persona, lambasted in America as gastro-porn, seems not so much an act as a slight camping up of her animated, playful self. She squirms when I mention the finger-licking, says she never watches herself on TV, that her sex symbol status is

over-wrought: “What is appealing to men is that mixture of love and mother, someone who will cook and care for you.” Although, in truth, most men are looking past her cupcakes down her cleavage. And unlike other women celebrities known for their voluptuous curves, who turn out in person to be just large breasts on stick torsos, Nigella is, as advertised, a properly big girl. This is a body born in the wrong age. Her bosom (reportedly 32G) and full bottom synched by a delicate waist, is made for basques, bustles and bodices. Although Nigella would loathe the formality and restraint since she bins, on principle, all black-tie invitations and doesn’t even wear knickers. Really, never? “I don’t need to because I always wear a long skirt,” she says, adjusting her black jersey Wallis ankle-length frock, one of five she wears in rotation.

There is no filming today, so Nigella has only her personal assistant Zoe and home economist Hettie in attendance. They are cooking lunch, as they do every day. “We have a full table. There’s normally about five of us,” says Nigella. “Sometimes friends drop by. Ruby Wax got God a bit after the tsunami because she was spared – God truly works in mysterious ways! – and she decided to do work at the Royal Marsden on Tuesdays so she’d come round on her way.” A posh chicken has been roasted, Nigella has brought bread sauce from home and is opening a bag of salad, dropping lettuce on the floor. Her untidiness tortures the fastidious Hettie. The ambience is somewhere between Austen’s Bennet sisters and Cleopatra with her handmaidens: informal, bustling, female, but there is no doubt who is head girl. “I run a very maternalistic society,” she says. “I say to the girls, ‘Have a baby, I’ll provide the childcare, I’ll get you a nanny.’ I’m desperate to be a granny.” As we sit for lunch at a table laid with Nigella own-brand plates and salad servers, she enthuses about her new premises. “It’ll be something to fall back on when I’m an old bag,” she says. “I can rent it for shoots or something. I never plan ahead but, who knows, one day it could save me from financial calamity.” Her two assistants chew their food silently. It is clearly ridiculous that a best-selling writer, with a burgeoning empire, from a wealthy family and married to an art collector worth an estimated £70 million, should worry about impecunious old age. But this place represents a lot to her: security, self-reliance, maybe freedom.

There have been suggestions that Lawson had trouble adjusting to her new life in the orbit of such a powerful – and, some say, controlling – man.

While no one disputes the couple’s connubial bliss alone, their joyful supper-in-bed intimacy, gone was Nigella’s ever-present gang, mates dropping by for pot-luck suppers. Nigella grew up one of four siblings, she loves a party, needs people around, abhors her own company. Perhaps this is a place to escape the grandeur of Eaton Square with its museum pieces and the predominance of Saatchi’s taste, to recreate something of her old life, not just for the cameras but for herself?

She doesn’t entertain at home so much now. “You get older,” she says. “It’s less studenty than it was. The gang always hanging around the kitchen table is a continuation of your student days. There’s a bit less of that, I suppose. But there is still some of the old gang. When we go on holiday next week Maria [McErlane, the actress], who was one of John’s best friends, is coming along.

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