If Stray Cats could purr, they likely would be heard all the way back in Massapequa. Two and a half years ago, three believers turned their back on an unimpressed New York and left for a larger island, England, where the fashion-conscious British embraced the Cats' exaggerated and vivid '50s style as the reincarnation of the true rock spirit.

Last night the Stray Cats' lead guitarist, 23-year-old Brian Setzer, sat on the edge of a bed in his Washington hotel suite, semiperoxided pompadour slightly disheveled. Bassist Lee Rocker and drummer Slim Jim Phantom, both 20, slouched in nearby chairs, their petulance and energy idling, anticipating a night of Brylcreem Bop at the Warner. Like their music, the Cats are lithe and lean, as if they've done away with all flesh to get to the bare bones of '50s-style rock 'n' roll.

"When we started out in Long Island we took a lot of c---," Setzer laughed. "We couldn't walk around town the way we were dressed. Now, of course, we're famous on Long Island. But when the three of us got together and played with this sparse drum set, stand-up bass and big fat guitar, wore baggy suits, big pompadours, tattoos and earrings, it was too much for those kids. A lot of the guys looked at us like we were from Mars. Of course when they heard the music, they just had to give in to it, it was just . . . rock and roll."

This last phrase was spoken with the reverent energy baseball fans use when speaking of the Brooklyn Dodgers.

Once they were overseas, the domino theory was finally realized: First England fell, then France, Finland, Italy, Germany, Australia, Japan. Yet despite their superstar status there, when the Stray Cats appeared on the now-defunct "Fridays" a year ago as virtual unknowns, the group was the first to get such a shot without an American record contract.

Now the group's American recording debut, "Built For Speed," is a kitty whisker away from the No. 1 spot in the charts, its shows are instant sellouts (the Warner sold out in an hour strictly by word of mouth) and its immaculate coiffures and flashy clothes are a such a hit stateside that the Stray Cats have moved back after two years in London. But, Setzer insisted, nothing much has changed. "Back then I was doing the same things I do now -- cars, motorcylces, girls, rock and roll, clothes, records. What more is there to life?"

Like the rockabilly music and spirit the group has championed, the Stray Cats are not particularly eloquent, but they are definitely fervent, as if their pulse came from an electric socket ("That's how we get our hair to stand up," Setzer smirked).

It is a private enthusiasm gone public. What's ironic, of course, is that the Stray Cats' success far outstrips that of the pioneers of rockabilly who inspired it--Gene Vincent, Eddie Cochran, Carl Perkins, the Burnette brothers; it's doubly ironic that even this newfound success was not "Made in the U.S.A." Then again, American roots music, whether rockabilly or soul or jazz or bluegrass, has always been better cared for and appreciated overseas. "People here are just not aware of rockabilly," Setzer complained. "In the '50s all they had was Pat Boone and Bobby Darin. Besides Elvis, none of the rockers ever really made it: Buddy Holly wasn't really recognized; Gene Vincent, Eddie Cochran, they were underground. People opted for the milder stuff."

It's the wilder stuff the Stray Cats are made of, even though rockabilly is the raw country side of early rock 'n' roll, simple music simply played on simple instruments: The guitar is the only melodic instrument, and there are few affectations. Everything is spare but the energy and it gets people dancing, pumps up the adrenaline, releases inhibitions; it is fool-efficient, sheer '50s vitality refracted through the toughness and visual flair of the '80s.

"And it's louder," Lee Rocker pointed out. "No one ever really played it quite that loud. We just have our own brand. Musically we don't change too many things--it basically sounds like it did when it was first recorded, but lyrically we update it."

The passion for true fashion extends to instruments as well, from Rocker's acoustic double bass to Slim Jim's spartan drum kit: "A snare, bass drum and cymbal. That's all I've ever used. It's all I know how to use, but that's all they had on those old records." Lee Rocker's slapped bass takes a lot of abuse: He jumps on it, plays it while standing on its sides and generally treats it like a reluctant square-dance partner. "They keep breaking," he said with a sigh. "They're just not as strong as they look." Setzer plays a 1953 Telecaster, "which is a little funky because it's not exactly 'state of the art.' But I think that's part of it--you get a rock 'n' roll guitar, stick it through a Fender amp, and there ain't a much better sound you're gonna get."

That its success came in England, which the band moved to as "a fling, an adventure," is not the usual career progression, though its results are similar to those achieved by another American power trio, the Jimi Hendrix Experience, 15 years earlier. Now as then, fashion rules in England and nothing is more fashionable than an immaculate rockabilly coiffure made greasy-gleamy by Nu Nile Hair Slick Dressing Pomade, set in tumultuous place by a blast of Final Net and animated by gum chewing, cigarette dangling and an occasional nervous twitch.

It was old-fashioned rock flash, with a different edge--"cool cat" style (in fact, the Stray Cats must have thought they were part rabbit because there soon appeared Alley Cats, Polecats, Rockats and Blue Cats).

British fans have traditionally been susceptible to high style, dance music, and the spirit of escapism. "They're more conscious of it there," said Slim Jim. "All the kids are dressed up as something, in one style or another. It's very important: They dress up like their favorite bands--there's a lot of Stray Cats running around." And unlike America, where people dress up only at night, "they do it 24 hours a day, they live the role. We live it, too. I wouldn't go out without my hair greased up, really."

Now the Stray Cats have come home, which is where the hard cash is. Next week, 22 weeks after its release, "Built For Speed" is likely to hit No. 1, though the Cats find nothing wrong with being No. 2, particularly since American radio has resisted them.

"The kids liked us and knew about us by word of mouth, but radio wouldn't play us," Setzer said. "But after a while they just had to. It finally happened . . . last week," he added with a laugh, "when we were No. 2. Even when we were top-20 many still didn't play us. College radio and MTV (the cable video music channel) were the only two sources that were hip to us; promoters couldn't understand why we had no air play and were selling out on our first tour."

So for now, the Stray Cats continue to pledge allegiance to the myths and energies of rock 'n' roll's first generation. They still sculpt their own hair, they still travel in buses that break down, they still perform eight months of the year.

They are pioneers of the past, using ancient energy, giving it new songs, new dreams. And stepping out to relive the raw instincts and wild spirit of rock 'n' roll every night. "That's what we live for, that hour on stage," says Setzer. "Most of the other things are just extraneous."