East side, west side, and from stem to stern of jolly old Britain: through dewy meadows and merry music halls, stuffy parlors and lady's chambers, and down to the sea in ships rollicked the King's Singers on Saturday night, re-establishing their firm hold on their Utah audience. By the evening's end, everyone in the sold-out house was eating out of their hands and would have done so quite literally if they could have gotten close enough.

What's the secret of the Singers' success? The voices are nice and even good but not extraordinary. But when you combine their amazing vocal mastery with their sure-fire audience rapport, you come up with a winning formula. Actually, "formula" may be an ill-chosen word, since whatever they do seems fresh and spontaneous, as if new-minted at the moment.They are vocal actors of wit and cleverness, imagination and free-wheeling versatility. The combination of two countertenors, a regular tenor, two baritones and a bass makes a different-sounding ensemble that's full and bright, and their diction is totally clear, with never a word lost. They introduce their music with just the right amount of engaging commentary, and they neither talk down to nor up to their audience.

Apparently the charter and senior members have a standard that they insist upon, and this group is remarkably successful in maintaining its style and its unique resonance, though a few singers come and go. The charm and finesse you remembered from last year is what you still get today in a King's Singers concert.

Equally at home with orchestral accompaniment or a cappella, the singers alternated between the two, with an emphasis on the unaccompanied. They pronounced themselves greatly pleased with Utah Symphony and Christopher Wilkins' conducting, and there was little reason to doubt their sincerity, since all forces seemed to get along famously, without a hitch.

What do the King's Singers consider "the best of British"? Folk songs in exceptional arrangements, glees, hornpipes and ballads, and a handful of agile music hall hits by masters of the genre, and they made a good case for most of their choices.

Outstanding among folk songs was "The May Song," actually two tunes from Cornwall skillfully blended, and a stylized narrative of the love death of "Barbara Allen," arranged by Rutter. "Bobby Shaftoe" and "The Oak and the Ash" benefited from distinctive arrangement by G. Lanford, and in "Jack the Jolly Tar" the singers told the story of a funny little seduction, passing the conversation nimbly from voice to voice. "The Skye Boat Song" was sung straight and beautifully, and "The Drunken Sailor" broke into a marked, raucous beat.

"Masterpiece" by Drayton was the stuff of a King's Singers classic, a 10- minute sketch of master composers, usually combining name and theme - a fugue on Johann Sebastian Bach, ground bass and running triplets for George Frederich Handel, stentorian Beethoven, a Strauss waltz with instrumental mouth noises, and a raft of French impressionists interrupted by peals of Wagnerian grandeur.

Not entirely successful was the Victorian collection - true to style, but with songs too often dangerously dated. In some of these, sentimentality triumphed, as in "There Comes a New Moon" (a song Gilbert and Sullivan might well have lampooned), "Goodnight, beloved" by Pinsuti (just this side of maudlin), and "The Goslings" - cute, but close to becoming precious.

But everything sprang back into shape with some witty, down-to-earth rock and music hall tunes. The Singers let it all hang out in "O-bla-di, O-bla-da" by Lennon and McCartney, gave Flanders and Swann's "Misalliance" a whimsical twist, and provided a dash of bitters to a peppy Noel Coward rumination. Offbeat McCartney emerged in "We'll All Stand Together," celebrating the true blue loyalty of a bunch of frogs. Nor did they taper down in their encores, which included the rousing "Nouveau Poor" by Peter Christy and the Overture to "The Barber of Seville" with vocally simulated instruments.