In a season of scanty eveningwear, we're asking miracles of our lingerie. And we're getting them, says JAMES SHERWOOD
How thin is too thin? In the past weeks, we've seen the nation's style press initiate a weight-watchers campaign against a certain Mrs Beckham from Manchester. Many women drop a few pounds after pregnancy. Few women perform in nationwide stadium tours and have to carry their own weight in Gucci carrier bags on a daily basis. Only Mrs B "works out" with a sex God footie player every morning. Style Police detects the Green Eye'd Monster at work. Yes, Linda Lee Potter of the Daily Mail has it in for Mrs B because Posh is too rich, too thin and too, too divine.

Some women are naturally thin. We are bound to be a little jealous of skinny chicks this season because winter eveningwear is practically non- existent. Handkerchief tops are held together with a cat's cradle of spaghetti straps. Prada gave us the winter bustier, Emporio Armani presented the tape measure-thin sequin bandeau top and Dolce e Gabbana raised skirts 6in above decency. Posh is particularly fond of the look-no-bra handkerchief top. The only girl who can carry off a handkerchief top is one with look- no-breasts.

Regardless of whether you dare to bare this winter - and it is winter so, hello?, what's with all the naked flesh? - at least the fabric shortage in this season's eveningwear prompts the great lingerie debate. When fabrics are sheer and the silhouette clings you're going to need to dig those foundations deep. Lingerie is the chartered surveyor of fashion. Even if you're wearing a skinny-rib knit polo neck your lingerie is going to make the difference between solid foundations and landslide.

If Style Police were on Mastermind, women's underwear wouldn't be our specialist subject. So this week we consulted the oracle, Fenwick of Bond Street's lingerie guru Mary Flack. What this woman doesn't know about scanties ain't worth knowing. "Comfort comes first," says Flack. "The golden rule is if you can feel you are wearing underwear then there's a problem somewhere. The major innovation is seam-free underwear. We've just had a delivery of Triumph's new Simply Soft bras (left) which are completely seam-free, even over the straps. They are laser-cut in microfibre and react to body heat by moulding into a perfect fit. Microfibre fits like a second skin and is almost invisible even under sheer clothing."

The major story in lingerie land is the removal of construction. Bras are no longer built like cantilever bridges. For the present, 80 per cent of bras are underwired, reports Flack. The body-heat microfibres may change all that. The other great debate raging in Fenwick's lingerie department is G-string versus deeper knicker - which is best at banishing VPL? Flack reports a 50/50 neck-and-neck race. "The thong is very popular," she says. "Most bra companies will make a set with a thong and a knicker now. Basically, the thong - if well made - is comfortable and practically invisible."

How to wear it

Women expect their lingerie to be more versatile than Inspector Gadget these days. It has to be functional, comfortable and - occasionally - miraculous. Now boobs are back, women all want cleavage like Sophia Loren's. Triumph and Gossard will both perform this levitating act with aplomb. And it's not just up top than women are demanding a little extra support: Fenwick is selling masses of Wolford support tights, which apparently achieve in a minute what would take a personal trainer years. Marks & Spencer have patented the Secret Support T-shirt with in-built mesh that means you can wear it bra-less without going into free-fall.

The lion's share of underwear sales are still in black, white and natural. "But women do want a shot of colour if they want to feel glamorous or maybe the trim on a bra will show under a dress or sheer top," says Mary Flack. "Lingerie is in step with fashion, so we're seeing a lot of very delicate embroidery, pink satin trims and pretty prints."

Where to buy it

The cardinal sin of lingerie shopping is not knowing your size. All the Fenwick lingerie angels are trained to fit. Fenwick is the Quality Street selection of Christmas lingerie. Style Police recommends Calvin Klein's cK gossamer-sheer bra (pounds 26.50) and brief (pounds 15) sets with discreet diamante applique. The miraculous seam-free Simply Soft bra by Triumph is a mere pounds 15. The Shopgirl lace-trimmed vests, tops and knickers have completely reinvented thermals. Produced with Damart, these pieces are sex kitten cute in vampy colours (pounds 35 for vests and pounds 14.95 for briefs).

You know that Style Police's heart belongs to Janet Reger when we're talking luxe lingerie. The best newcomer award goes to Eda who source the frothiest Swiss embroideries for what you'd call boudoir lingerie (from pounds 15 for briefs and pounds 35 for bras). We particularly love the fit service at Eda, where they will alter all underwear to work with a particular knock-out frock.

You can't diss Marks & Spencer's knickers. They've collaborated with Agent Provocateur to produce the Salon Rose range (from pounds 6 for knickers and pounds 14 for bras). Meanwhile their classics are still classy and the Secret Support T-shirt, good enough for outerwear, a mere pounds 19.99. A final word on "cheating" lingerie. Boys can now do squeeze it in, push it up and stick it out underwear with Top Man's new Block & Tackle label. So it will be a surprise for both of you when you unwrap the latest lingerie.

Address book

Eda (tel: 0171 584 0455).

Fenwick of Bond Street (tel: 0171 629 9161).

Janet Reger (tel: 0171 584 9360).

Marks & Spencer (tel: 0171 935 4422).

Shopgirl (tel: 0171 437 1259).

Top Man (tel: 0800 731 8288).

Triumph (tel: 01793 720232).