Winning choices from London

Have all the women in Britain joined the police force? A visitor this autumn could be forgiven for thinking so, because the streets will be a sea of navy blue.

It's the surprise winter color, and it's going to be everywhere. Some of the handsomest coats - big, loose, swirling ones; neat, lean, double-breasted classics as well - are in it. So are trousers (cuffed now - that's important) and narrow coat dresses and silk overshirts. Even many of the knits star navy, frequently tweedy with a mix of gray.

Gray and black are the other autumn winners. A bright claret, a few touches of rose (checked in with those grays for snug little collarless wool jackets), and the odd piping in saffron freshen up the somber spectrum.

These low-key colors are often married in rustic stripes with more than a hint of Irish folklore. The longer skirts look good in this, often with stitched-down pleats, very boxy. The dark mixtures are, of course, a British fashion answer to the sweeping influence of new Japanese fashion on the scene, and the richly textured cottons, often woven in diamond pattern, reflect the same obsession with things from the Far East.

The kimono sleeve keeps on, so most of this autumn's sweaters are roomy, but they offer two sorts of lines. Some are almost square, so that the sweater flops or juts out a bit, making no attempt to cling smooth to hip. Others have very wide welting, curve, and outline right over stomach and hips.

Flopping waterfall revers are important, and lots of loose jackets, whether knitted or of tweed, have this casual, throwaway touch. You get the same flopping collar, this time edged with a strip of diamante, in pretty after-dark dresses of polyester jersey - gray, wouldn't you know? These are part of a new collection by a top designer, Anne Tyrell, who has changed firms, and are teamed with fur fabric coats to tone - all in soft grays and taupes. They make smashing outfits which can of course be bought separately.

If you like your skirts long, you'll find them. Kneetop? That too. Buyers are hedging bets by choosing many lengths; manufacturers are doing the same. The long, narrow skirt is the career woman's choice, the mini her kid sister's. The safe midknee remains universally available for conservative women.

Alert stores are chasing the younger, avant-garde designers for these long, slim skirts, while the traditional big firms are playing it safe, still offering blouson jackets and ruffle-neck blouses with their tartan just-below-knee skirts. But some big-name designers, such as Roland Klein, show suit skirts some six inches from the ground.

An ethnic fabric that's having a good run, one unknown to most women so far, is a natural raggedy-stripe wool called Jacob's wool, from sheep of the same name. Sheridan Barnett uses it for long slim coats and plain matchingdresses. The ethnic look has indeed not died away.

While many a suit still harks back to British naturals, especially in the markedly upgraded clothes from popular chain stores (now getting very preppy indeed), you get more sleek sophistication from the new autumn dresses. Watch for names like Jean Varon and Monica Chong and Lumiere for the slim wool crepe dress, usually a chemise, you wear all day to the office and on out for the evening. It's the garment many career women have longed for.

Dolman sleeves are uppermost in these, and at Jean Varon one gets snake trimmings (dyed raspberry to match the wool), which happened also to be popular in the Paris couture. The designer here is also using an old-fashioned panne velvet he unearthed in a manufacturer's recently sold factory.

Other designers all over Britain are carving black velvet into suits, dresses , evening trousers, sometimes topped with all-sequin jackets or, much newer, the full-bloused sweater entirely of sequins in zigzags of copper and black.

British designers have had about enough of the taffeta of Princess Diana's ball gowns and are turning for festive wear now to stiff satins and jewel-sprinkled lace.