Now that George Balanchine is gone, Sir Frederick Ashton is indisputably the world's greatest living master of the classical idiom in ballet. However, since England's Royal Ballet -- the chief repository of Ashton masterpieces -- has not visited Washington or any East Coast city for three years, viewings of his work haven't been easy to come by. It is mainly to the Joffrey Ballet, which has been building an Ashton repertory for a decade, that we have had to look for recompense. And among the other anticipated rewards -- including John Cranko's full-length "Romeo and Juliet" -- of the Joffrey's imminent two-week engagement here, there'll be a generous helping of Ashton.

Joffrey's opening-night program Wednesday, in fact, will be a birthday salute (Ashton turned 80 on Sept. 17), a program embracing four ballets, followed on Thursday evening by the Washington premiere of "Five Brahms Waltzes in the Manner of Isadora Duncan." Both programs will be repeated in the course of the run, which launches the Kennedy Center's 1984-85 ballet series.

The five Ashton creations thus sampled cover more than four decades of his career. They range from the eternally popular "Les Patineurs" of 1937, a classical gloss on ice-skating couples in a park; to a witty portrait of a provincial French nuptial party in "A Wedding Bouquet," also from 1937; to the hauntingly surreal impression of poet Arthur Rimbaud in "Illuminations," from 1950; to the pristine poetic purity of the 1965 abstraction "Montones II"; to the rapturous evocation of Duncan in "Five Brahms Waltzes," dating from 1976.

Because both Ashton and Balanchine, albeit in quite separate ways, extended and amplified the choreographic tradition of Marius Petipa, the two inevitably invite comparison. For starters, they were born in the same year, 1904. Their lives also crisscrossed in curious ways, all the more striking in the light of their dual roles in dance history. Balanchine migrated from the Old World to the New, establishing in the process a new kind of American classicism. Ashton reversed the course, moving from the New World to the Old, where he became the principal instrument of a distinctively English classical style.

At a certain crucial point, in the mid-'30s, it might have appeared that things would work out just the other way around. Balanchine left Russia as a young man to join Diaghilev's Ballets Russes troupe in Paris. On the latter's death in 1929, he wandered about Europe for a while, winding up in London with a company he'd founded, Les Ballets 1933. It was there that the American intellectual Brahmin, Lincoln Kirstein, in search of someone to help create an American classical dance school and company, found Balanchine and persuaded him to share the experiment.

For his part, Ashton was born in Guayaquil, Ecuador, the youngest son of a British businessman. He grew up in Lima, Peru, and there attended a performance by Anna Pavlova. "Seeing her at that stage was the end of me," he once wrote. "She injected me with her poison and from the end of that evening I wanted to dance." After World War I, he was sent for schooling to London (he spoke English with a Spanish accent at the time), and against his parents' wishes began to study dance, first with Leonide Massine and then Marie Rambert, one of the seminal figures of British ballet (among her other pupils were Antony Tudor, the American Agnes de Mille, and John Cranko).

In London in 1921, he saw Isadora Duncan dance, another fateful encounter the memories of which were vivid enough to provoke the genesis of "Five Brahms Waltzes" more than 50 years later. In the late '20s, Ashton spent a year on the continent with Ida Rubinstein's company; there he met Bronislava Nijinska, Nijinsky's sister, whose choreography was to influence his own profoundly.

After his return to England, Ashton met Ninette de Valois, the founder of the Royal Ballet, and began to choreograph for her Vic-Wells troupe, as well as for Rambert's Ballet Club. Then, in 1934, he was invited to America by Virgil Thomson, to choreograph the opera "Four Saints in Three Acts" he'd composed on a libretto by Gertrude Stein. In itself, this was a historic production (more of which later), but it also poised Ashton at a significant crossroads -- he loved this country, although he greatly missed his own, and for a while toyed with the idea of staying here.

He went so far as to consult the reigning dance critic, John Martin, who told him, as Ashton has recounted, that there was no place for classical ballet in the United States, which was at least close to the truth at the time. And so, the very year that Balanchine made his first ballet ("Serenade") for the company he and Kirstein had formed here, Ashton returned to England for good. The next year, de Valois appointed him an official choreographer of Vic-Wells (later the Royal) Ballet, and the first ballet he created in his new post starred the young Margot Fonteyn, whose career was to be so closely entwined with Ashton's thereafter.

Thus does destiny play its little jokes. Ashton himself, among many others, has wondered what might have happened if he'd stayed here, and by the same token one speculates on the consequences had Kirstein not lured Balanchine from London. Their paths intersected significantly one more time, when Kirstein invited Ashton to choreograph for the fledgling New York City Ballet in 1950 -- the result was the extraordinary "Illuminations," which, at the time, the New York critics loved and the British pundits disdained.

As makers of dance, Ashton and Balanchine have much in common despite their distinctive choreographic traits, whose differences may seem largely a matter of emphasis -- on characterization and poetic atmosphere for Ashton, on the pure logic of musical syntax for Balanchine. Yet the following words from an Ashton essay, expressing his choreographic creed, might as easily have come from Balanchine's mouth: " T aking one's lead directly from the music . . . is the method which I now prefer. Through it one gets the purity of the dance expressing nothing but itself, and thereby expressing a thousand degrees and facets of emotion, and the mystery of poetry of movement . . . In a ballet it is the dance that must be paramount."

Another particular that links the two is their similar involvement with vernacular dance. Ashton's first ballet, in 1926, was created for a London "revue," and in the early '30s, both Ashton and Balanchine were choreographing ballet routines for London cabarets and music halls. Especially during his earlier years in this country, Balanchine worked a great deal on films and musicals, one outcome of which was the now successfully revived "On Your Toes" of 1936.

In London, meanwhile, Ashton frequently staged variety shows with a black American collaborator -- the tap and jazz dancer Buddy Bradley, who'd worked for Ziegfeld and devised dances for Eleanor Powell and Ruby Keeler. Balanchine's innovative 1940 staging for Broadway of the all-black "Cabin in the Sky," enlisting the help of Katherine Dunham and her troupe, had its parallel in Ashton's contribution to "Four Saints and Three Acts," with a cast of six black dancers -- Ashton recruited the three men from among the Lindy hoppers at Harlem's Savoy Ballroom.

Though Ashton has not been quite as prolific a choreographer as the prodigal Balanchine, his range of means and modes is almost as great, as even the limited sampling of the Joffrey Ballet's Kennedy Center programs confirms. It's not easy to summarize Ashton's genius, but perhaps the citation for his Dance Magazine Award of 1970 gets to the heart of the matter: "A choreographer who rounds the corners of classic austerity with a romanticism so tender and so completely British in its good manners that we all proudly deem it international."

Also on tap for the Joffrey run is the Washington premiere of Gerald Arpino's tribute to the Southwest, "Jamboree," commissioned by the city of San Antonio; other ballets by Arpino, Paul Taylor, Laura Dean, Jiri Kylian and William Forsythe; and, starting Dec. 12, the premiere of the first American production of John Cranko's "Romeo and Juliet."