Neville Marriner and the Academy of St. Martin-in-the-Fields." The name rolls off the tongues of radio announcers with sonorous regularity, splendid and redolent of baroque orchestrations heard in the shadowy glades and gilded halls pictured on record album covers.

Nearly 20 years and 200 records after its founding as an occasional chamber music ensemble at the church of St. Martin (whose early 18th-century fields have long been replaced by less than bucolic Trafalgar Square in the heart of London), the Academy is now perhaps the most comprehensively recorded chamber orchestra anywhere. Listening to WGMS-Bethesda or the BBC's Third Programme, sometimes it sounds as if the group must spend their entire lives holed up in the recording studio.

At its helm is Neville Marriner, his own sonorous name inseparable from both orchestra and image. A former London Symphopny violinist and music director of the Los Angeles Symphony, he is a squarish man of medium height who looks rather younger than his 53 years. He is jaunty, showmanlike, but an economy of movement in his conducting suggests no-nonsense musicianship. And he looks as if he hasn't had a new dinner jacket in years.

"It's such a silly name that I suppose people do remember it," says Marriner, musing about the Academy in his highceilinged Regency flat in South Kensington (he also has a 17th-century house in the lush Devon countryside find a "very Jane Austen" house in seaside Lyme Regis). The walls are lined with books and pictures, and some of the-furniture is baroque. Through the high windows is a view of a small, very green park. Many passers-by appear to be in Arab dress.

It is easier to understand the Academy if one first discusses what it is not. "We get many, many inquiries saying, 'Can we come and enroll in your Academy?' says Marriner. And many people are bitterly disappointed when they find that the church of St. Martin isn't in the fields. We actually did a tour once calling ourslves 'The London Strings,' something much worse, something awful. I don't suppose we'll change it now, but, you see, we never thought our first concerts would be our last. I remember very well, it was November - Friday the 13th, too - and a very foggy night . . ."

A group of musicians, may from the LSO (in which Marriner played first-chair, second violin), decided to give a few chamber music concers in the new vigorous manner propounded by musicologist Thurston Dart.

The group's harpsichordist, who was also the organist at St. Martin's, suggested they perform in the famous church, and the vicar of St. Martin's suggested they call themselves an "academy" in the manner of Renaissance and 18th-century dilettanti.

The concerts became popular, and in 1960, Australian wool millionairess Louise Dyer, who owned the French recording company Oiseau Lyre asked the Academy to make some records for her. "Not very good ones," says Marriner, "but they were well-reviewed." And so the orchestra was launched, although it remained for them to develop a distinctive musical style, expand their repertoire, and become not only self-supporting, but one of the highest paid orchestras around.

"I'm never completely flattered when someone says, 'I heard one of your recordings recently - I knew it was the Academy. I can always recognize your style," says Marriner. "It is, of course, a very deliberate style, really an attempt to inject vitality into much of the repertoire we had learned to play rather drearily. Baroque music had come to be associated with a forced docility and gentleness. But just after the war, several musicologists. Thurston Dart among them, advanced the idea that baroque music was really very virile, very lusty. Gradually the public taste began to change."

And it so happened that the Academy's repertoire coincided with the format of the BBC's original Third Programme, which emphaiszed 17th-and 18-century baroques music and contemporary works, often by British composers such as Vaughan Williams, Elgar, Delius and Tippett, a particular favorite of Marriner's. Curiously, their repertoire also happened to split up readily into small pieces, about 15 minutes in length, which Marriner describes as the appropriate length for the attention span of "a general radio audience, a sort of wallpaper audience."

An "entirely fortuitous" conjunction, Marriner says, and adds, "The Academy has flourished on undersell. It has no pressure group to further its cause." Others in the music business might take exception to such a claim. "Of course, they have been built up by Decca records," says a BBC music producer. "And I think you could say their popularity can be attributed first to the quality of the recordings, the performances always meticulous, beautifully phrased, very euphonious. They sometimes lack a little depth of interpretation, I think, but there is a sort of suavity of performance, a polish which people seem to like."

Neville Marriner finds it "tedious" to be typecast or categorized. He is full of nervous energy, smoking - or rather, not smoking, but lighting - Henry Winterman small cigars, fiddling with a matchbook. He has a horror of anything "boring" or "dreary," and has found in his own career that "10-year plans are too long and five-year plans too short," which means the next year or so will see certain changes in the Academy.

"We have always been a democratic group, with everyone offering suggestions," he says. There was even a time when he led from his violinist's chair. But he has become increasingly interested in conducting, particularly in conducting symphony orchestras, and will spend less time with the Academy in the future, except, of course, in the recording studio. The Academy now has what he calls a "quasi-exclusive" contract with Phillips (Phonogram) for 200 records, as well a contining relationship with Decca's Argo label.

But on stage, at least, Marriner will detach himself and leave the directing to concertmistress Iona Brown, who has been with the group since her performance so far, expecially as she is the very embodiment of style - striking in appearance and full of stage presence. "A most effective performer," he says, adding, "We are very fortunate that she looks good, too."

The Academy's greatest fear these days, says Marriner, is of "getting stuck." He forsees a change of repertoire as well as a maturing of style, with less concentration on early baroque music, which he thinks will be recorded mainly with original instruments in the future. "It used to be that the only people who were interested in the baroque were - what did we call them? - 'open-toed sandal and brown bread people,' the sort of people who, if they weren't terribly good pianists, took up the harpsichord. Rather dreary, earnest people, technically not very good. But that isn't true today. I would like to see the Academy become more a Mannheim orchestra - Mozart and Haydn - rather than Vivaldi and Bach."

If the Academy has an essential charateristic, perhaps it is efficiency. Far from spending every day in the recording studio, the group can manage 20 records in 60 days. "Three days on and one day off," says Marriner. "That way it's possible to keep sounding like a live body rather than a dreary bunch." Openly, perhaps "immodestly," proud of the group's success, Marriner says, "We are rather a thorn in the side of the Arts Council and the British Council, I think, which are fond of putting money into what I consider falling organizations. They ought to invest in successful enterprises and make them more successful," No one can quibble with the Academy's success today; the records they make show a profit within a month.

And probably no one would quibble with the efficient organization of Marriner himself. "The idear of growing old as violinist never appealed to me," he says, "and the idea of growing old as part of a string quartet never appealed to me. But I would like to grow old as music director of a symphony orchestra, and that requires long-term views, of course."

He recently resigned his post as music director of the Los Angeles Chamber Orchestra in order to begin a spate of symphonic guest conducting, particularly in America. In the coming year, he will apperar with the Boston Symphony Orchestra and the New York Philharmonic, and next year with the Cleveland Orchestra.

He won't spend much time in Devon, it seems. In the course of an hour or so, Mrs. Marriner, who manages his schedule and used to look after that of the Academy, as well, has answered the phone at least four times. The Marriners have a son and daughter, both in their early 20s, but "no pets - though we used to, of course."

Neville Marriner is certainly not the only musician or the only man of taste in England with a head for business. But his good sense, efficiency and driving perfectionism may have been largely responsible for the rise of the Academy from a talented, threadbare chamber orchestra, giving the odd concert after evensong, to one of the most widely recorded, played and heard musical groups in in the world.