I am officially a Lady Who Lunches! It's an epithet I've always fancied, but never tried on for size - chiefl y because authentic Lunching Ladies tend to have a husband in banking, a chalet in Verbier and a forehead in a permanent state of Botox-fed paralysis. But here I am, at the Berkeley Hotel, lunching in grand style with the drop-dead fabulous wife of Gordon Ramsay.
Tana is one of those women who make you feel as though you should have ironed your hair, or at the very least had a quickie pedicure, before you arrived. She is 30, with a figure like heaven - and that's after four children and almost half a lifetime with the irascible Mr Ramsay.
We're in the Boxwood Cafe - next door to her furniture shop - to sample the 'Beauty in the Box' menu. It is about as fashionable as feeding gets, partly because it's in Knightsbridge, just a yodel from Harvey Nicks, but mostly because everything on this finely calibrated, seven-course menu is going to make you younger, thinner and better at chess. There are Omega 3s galore, fish for brain food, selenium and lesser known minerals to startle a recumbent form into activity. And (they're going to love this in Chelsea) it's all presented like a gastronomic couture show.
Now, a seven-course meal, in the general run of things, would be enough to scare the average Lunching Lady out of her Jimmy Choo sling-backs. I once had lunch at Joe's Cafe in Brompton Cross with a matching set of fashionistas, and I was amazed at how long it can take a girl to get through a leaf of radicchio. It was like being in a fi eld with three very elegant but undernourished heifers chewing the cud. True to form, I committed a cardinal sin by ordering a side order of chips, and then spent a guilt-ridden lunch eating them with mayonnaise and ketchup while the others main-lined San Pellegrino and talked about shoes.
There are, needless to say, no provocative chips on the Beauty in the Box menu. Nor anything as de trop as wheat, dairy or sugar. Instead, head chef Stuart Gillies (late of Le Caprice) has fashioned a delightful smorgasbord of mini bites, each element designed to offset the dumpling effects of over-indulgence and fatigue (oh, bring it on!). There's chilled carrot, ginger and ginseng soup to keep skin supple and soft; there's pan-fried fillet of Cornish mackerel, with watercress, green bean and sesame salad and a soft boiled quail's egg (that's Omega 3s, protein and essential minerals from the fish; iron and lecithin from the egg to stimulate cell growth; iron and the wondrous Vitamin C from the watercress). Even the pud - a Vahlrona 70% chocolate fondue - is high in antioxidants.
All blissful, but I couldn't help feeling that we ask a lot from our food these days. It used to have such a carefree, simple life. Its mission was to fill you up sufficiently to fuel a pot of hunting and gathering. More recently, its job description got rather more complicated. Ever since antioxidants and free radicals waltzed into the lexicon, we've been scrabbling around in the fruit bowl for blueberries and strawberries and broccoli in a desperate bid to ward off the horror of ageing. After all, who needs to splurge on Clarins, or a facialist, or a surgeon's scalpel if you can access eternal youth with a humble grapefruit? And Tana - surely a heavy user of pomegranates - certainly makes a persuasive advert for healthy eating.
'It's vibrant food,' she says between dainty mouthfuls of oscietra caviar (essential fatty acids). 'It actually gives you energy. You can spoil yourself without the guilt.' I agree, and launch a chunk of papaya (betacarotene, vitamin C, potassium) into a tiny fondue of molten chocolate (magnesium, flavonoids, all-round deliciousness). 'This lunch,' says Tana, 'is like having a spa treatment. You come away knowing you have done yourself some good.' Ramsay's right (though I notice her fondue is rather fuller than mine as we part). I leave the Boxwood feeling refreshed and about 35 minutes younger than when I first arrived. I shall share this with the heifers when next we meet.
· Beauty in the Box, £55, at the Boxwood Cafe (020 7223 8086)