US designers recall the days of Anglo-Saxon grandeur with low-waisted elongated lines as the silhouette for next season; FALL '82: NEW YORK

The aura of good breeding has not been accorded this much respect in fashion circles since kid gloves and calling cards were requisite equipment for the modish lady. Well-mannered clothes of the sort once favored in the higher reaches of society have been greeted with ringing applause here at recent showings for next fall.

The epitome of such elegant understatement may well be an offering presented at Ralph Lauren. What, after all, beats the perfection of a beautiful navy cashmere pullover worn with a matinee-length strand of cultured pearls (of a size that is neither too ostentatiously large nor too apologetically small) and gray flannel trousers of impeccable cut?

There have been other analogous examples of superlative restraint that have brought store buyers to their feet at Calvin Klein and Anne Klein's openings -- and occasionally at the Perry Ellis show. Upper-class quality dressing seems now to be the ruling order of 1982 fall chic.

The prevalence in the leading American collections of excellent tweeds, fine silk velvets, and laces that appear to have been inherited from some illustrious forebear is quite possibly due to the mood engendered by audience reactions to ''Brideshead Revisited'' on television and ''Chariots of Fire'' in the movie theaters.

The women's costumes in both these productions are columnar in shape. They have much in common with the low-waisted elongated lines proposed by US designers as the preferred silhouette for next season. The turnouts composed of stretched-out Norfolk jackets and mid-calf envelope, or knife-pleated skirts at Ellis and Anne Klein, are cases in point.

Adaptations of menswear worn in the films are frequently done, too. There are many old school ties, roomy blazers, sweaters bordered with team stripes or patterned in Scottish argyle or Fair Isle motifs. Ellis has a whole lighthearted series of clan plaids -- different tartans scrambled together rather engagingly in single outfits, all the way to the accessories that include plaid flat-heeled shoes with contrasting argyle socks and mufflers.

For evening, there are feminized versions of men's dressing gowns of satin with monograms, piping, and fringed sashes, as well as tuxedos for big nights on the town. The latest in dinner-jacket dressing for women leaves out the shirt and the black tie, though. Models just wore the suit. The jacket is generally an attenuated sack coat that comes over pants or a wrap skirt, and it has only one button or two below long narrow lapels. Lauren did the look as a coat dress.

Above all, there is the 1920s male's oversized raglan-sleeved topcoat, a martingale usually belting the back, which is tossed over everything from country checked wools to sleek charmeuse. This capacious outerwear has the well-known charming looks of the too-big Brooks Brothers shirt a girl borrows from her brother.

While the recall of the days of Anglo-Saxon grandeur is a dominant theme, wearing a Lady Marchmain hat, high laced-up boots, or a starkly plain decollete black velvet flapper dress with pearls and above-the-elbow white kid gloves (which Lauren actually showed) will not be obligatory. A fair mixture of other choices exist, judging from the first week of the fortnight of Seventh Avenue showings.

Some new styles strike a Fifties Revisited chord. British journalists who came over to preview the American fashions that will be sold in London thought the full-shouldered suits with fitted waists and slender skirts by Calvin Klein and Perry Ellis were ''quite like Jacques Fath,'' the Paris designer whose look was popular three decades ago.

In another vein, Lauren's pictorial sweaters and full skirts made from antique patchwork quilts were a distillation of Americana. Elizabethan influences were hinted at elsewhere via pleated ruff collars, capelet yokes, lace fichus and jabots, and lapels cut on the bias so that they form a rippling flounce.

Although designers concentrated on long lean clothes, American customers will find a liberal share of flared shapes, too. The double cape shown by Calvin Klein in brick wool as well as black and camel, conservative coloring being a point in his collection, is perhaps the most generous of the circular cuts.

The knee-grazing skirt is well-represented in the fashion array for fall, and there is a sprinkling of ultra-short skirts. Like Bill Haire's puffy mini of quilted leather, the little skirt is nearly always accompanied by colored stockings and low cuffed or pushed-down soft suede boots.

Trousers are another strongly advocated alternative. Aside from the triangular-seamed architecturally-conceived kind produced by the inventive Ronaldus Shamask, experimentations with so-called ''funny'' pants have been put on hold for the moment.

Adornment is kept at a minimum in the New York collections. The beautiful fabrics have been allowed to speak for themselves. Halston sprinkles galaxies of nailheads over many of his clothes. But elsewhere the tendency is to focus the ornamentation on one spot. The diamente feather on the shoulder of the black dinner suit at Calvin Klein proves how effective the single bit of glitter can be.