A GLIMPSE OF SION'S GLORY. By Isabel Colegate. Elisabeth Sifton/Viking. 153 pp. $14.95.

WITH THE publication of The Shooting Party in 1981, Isabel Colegate claimed her literary territory: England in the golden years just before the Great War. The country house where the shooting party convened was the microcosm of British society; upstairs and downstairs, urbane and rustic, aristocrats, financiers and country people gathered at a moment all the more precious for their ignorance of the carnage to come. The "major motion picture" made from this lovely novel captured with uncommon fidelity the elegiac tone, the grief for an old order dying. Since then, many of Colegate's admirers have also discovered her earlier Statues in a Garden, whose venue is the same Edwardian society, its privileged certainties destroyed by the war without and the flaws within.

Isabel Colegate may be a social historian at heart, for these small, elegant novels are works of convincing class portraiture. In A Glimpse of Sion's Glory, however, she leaves the Edwardian world and ventures into three short stories with three quite different settings and situations. Her following will, I fear, be disappointed, not only because the territory is new but because the present stories range in quality from passable to inert.

"The Girl Who Had Lived Among Artists" examines the effect of a beautiful Bohemian young woman on her circle of friends and lovers. The time is 1938, the place the beautiful Palladian city of Bath. Professor Behr, a recent refugee from Vienna, complains of Bath's provincial calm: "No life, no art, no culture. Nothing but respectability." That respectability is an anxious condition as perceived by Vere Turner. His mother, ever striving for social vindication, comes from "a social level at which it was enormously important to know that there was a lower one," but the gentility Mrs. Turner longs for means very little to Vere. His flat-mate is Carley, a handsome working-class man who is one of nature's noblemen even if he has never set foot in a middle-class house.

Into their m,enage comes Nancy, to share Carley's bed and dazzle the sexually naive Vere. Beautiful, unconventional Nancy ran away with an artist when she was 15 and has led a Bohemian life ever since. Carley, Vere, and all the other tenants of their house warm to her sensual vitality; lines of age and class are blurred as she urges her friends to express their own sensual natures. Alas, this belle dame sans merci provokes a catastrophe that destroys Carley and reveals Nancy's fatal coldness.

THE NARRATOR of "Distant Cousins," a British writer of science fiction, has a house in Tuscany. On one of his walks in the hills, he happens on a small stone house where an expatriate American professor and his odd house guest offer their hospitality. The professor tells his visitor a long story which explains the oddness of Hal, the house guest: for Hal is the last survivor of a race of highly civilized beings descended "not from our own old mother ape . . . but from some other hominid . . . " Hal's shining civilization -- in a city built on the shores of a high mountain lake in Siberia, on the earth but not of it -- had many lessons to teach our own. In happier times, Hal described his fellow creatures as "the expression of the joy of the creative mind . . . we are the symbols which crowd the dreaming mind of the Creator." Alas, human interference destroyed that civilization forever, and Hal's race will die with him.

The title story, "A Glimpse of Sion's Glory," follows the fortunes of Alison, a well-bred, emotionally contained young woman, and the two men who matter to her. Oneis her husband Robert, so well suited to the practices of conventional society that by the time we meet him he has become an ambassador. The other is Raymond, ever drawn to the more extravagant of the social options available in the 1960s and 1970s. When Raymond was at Oxford he cultivated the persona of "odious young man." Since then he has enjoyed sex, drugs, scholarship, authorship, communal living, medical school, organic farming and general caddishness. He is, of course, Alison's unacknowledged true love. Alas, he effectively removes himself from her life when he makes his last flamboyant gesture.

All three stories have something to do with the brief glory suggested by the title, and all three end predictably in loss or disillusionment. None of them makes very satisfactory use of Isabel Colegate's gifts as a social observer; these are longish stories, but their scale is not well matched to the kind of ironic juxtapositions at which she excels. In her novels, the abundance of period detail fills the gaps left by rather superficial characterization, but these short stories lack that support. In each of them the reader is kept at a distance by the opaqueness of the characters. "Distant Cousins," the science-fiction story, must bear the added weight of sections narrated in the stiffest, most wooden indirect discourse.

Unfair as it may be to hope that an admired novelist will keep writing the same book, that is what many novelists very satisfactorily do. One wishes that Isabel Colegate had done so, and that A Glimpse of Sion's Glory made better use of the strengths that characterized her earlier works.