LONDON -- The Princess of Wales, Duchess of York and 21.5 million less-royal Britons watch it. The show has been a smash from Reykjavik to Barcelona. And starting Saturday on WETA, Washingtonians will have a chance to see what the fuss is about when Britain's top-rated television program, "EastEnders," begins a five-night-a-week, six-months run.

The soap opera, tracing the life of an East End neighborhood in contemporary London, is a phenomenon in this country. Launched in the fall of 1985, "EastEnders" has been the top nighttime program for more than a year. Its rating success has pushed the BBC miles ahead of its competitor, ITV.

More than that, like top-rated soaps in the United States, the program has become interwoven into the daily life of the nation. People talk about the show constantly. The traditional English Sunday lunch has been put in jeopardy because the BBC repeats the week's two half-hour episodes back-to-back Sunday at 2 p.m. Buskers in the subway can bring a smile to commuters and plenty of coin to their saxophone cases by playing the series' catchy theme song.

Like any good soap, the plot lines are too varied to explain, so the series will kick off with a special two-hour edition Saturday at 10 designed to get all the stories rolling. Thereafter, WETA will air the show at 11:30 weeknights.

Essentially, the series traces the lives of the people of Albert Square, a typical East End Cockney neighborhood. Life focuses around the local pub, the Queen Vic, run by philandering Den Watts and his tough but tender wife, Angie. At the Vic, the painful marital problems of the barkeeps, the extended family problems of the Beales and Fowlers, the racial problems faced by the Square's Indian immigrants and the discrimination faced by a gay couple are played out with a topicality unparalleled in television.

This is a soap opera with a difference. In Albert Square, if your marriage falls apart there's no jetting off to Acapulco with some Nautilus-bodied cupcake to sip champagne and get rid of the blues. Drinking problems? Drug problems? No Betty Ford clinics for these folks. You get what help you can from family and friends.

The show has more in common with Dickens than "Dynasty" or, as "EastEnders" creator Julia Smith says, "The show is much closer to 'Hill Street Blues' in tone than American prime-time soaps. We've got a core group of excellent writers, mostly young, who write for the theater, and give us high quality scripts."

A veteran of two decades of TV and one of the first women producers in England, Smith maintains fierce control of the program.

"The reason we're going on PBS, aside from my own commitment to public broadcasting, is I didn't want to have to edit seven minutes out of every half-hour episode in order to sell advertising."

Hyper-realism is the hallmark of the show. The exterior set is a stunning re-creation of a typical down-at-the-heels East End square. The interiors are decorated in perfect detail, right down to the graffiti doodlings by the telephone in the Vic. The laundromat reeks of soap; the machines really work.

Smith feels that the program's authenticity is the secret of its success, not only in England but abroad. "Look, we all live in the same century in the same world. The things that go on in Albert Square go on everywhere."

The emphasis on realism extends to casting. Almost everyone in the show is a real East Ender or, at least, a real inner Londoner. Peter Dean, who plays fruit-stall owner Pete Beale, said, "I've got a fruit stall in my background. I already know how to handle the props. "

The show's success has provided a field day for England's notorious tabloids, newspapers that make the New YorK Post look almost a model of restraint. After the Royal Family, their next favorite story is the "EastEnders" cast. Letitia Dean, 19, who plays Angie and Den's daughter Sharon, can't go out on a Friday night without turning up in the papers Saturday.

"I saw one of the editors of these newspapers on TV the other day, and he was denying that his paper was full of sex and scandal. He said, 'We only had four sex stories last year.' I said to myself, 'Right, I was three of them -- who was the other?'"

The papers do occasionally turn up truth. Leslie Grantham, who plays Dirty Den, does in fact have a dark past. At 19, he was convicted of murdering a taxi driver. He did 11 years in prison for the crime.

Just before the first episode was taped, Grantham offered Smith his resignation. The producer refused. "In a democracy and a Christian society, if you sentence someone to jail and they serve their sentence, the slate is wiped claen," she said at the time.

Smith expects the show to succeed in the United States. "I don't see why it shouldn't. It's been a success everywhere else." She is rarely wrong.

CONTINUED ON PAGE 8 EASTENDERS FROM PAGE 5 "EastEnders": from left, Queen Vic tavernkeeper Anita Dobson as Angie, Leslie Grantham as her husband Den, and Letitia Dean as daughter Sharon. 'EastEnders' Strives for a 'Hill Street' Tone Coming to Terms With 'Enders'

The biggest difficulty American viewers will have in appreciating "EastEnders" will be the language barrier. Cockney English is different from the English most British speak and is a dialect even more foreign to American ears.

A sample translation: "I was dressed up like a dog's dinner, but I got caught with me knickers in a twist because I left my readies at home" means "I was dressed up in my best suit but I was in a mess because I left my cash at home."

Then there is Cockney rhyming slang, an ever-changing secret tongue where you find a phrase that rhymes with a word and then drop the actual rhyming word to create a kind of logical gibberish that goes like this: "Let me get my titfer." Titfer is a hat, as in tit for tat, rhyming with hat. "Give that bird a butcher's" (butcher's hook, rhymes with look). "Met a septic the other night" means "I met an American" (septic tank, Yank). The variations are endless.

To help with translation, Lionheart Television International, the BBC's distribution group in the United States, is providing a glossary to PBS stations carrying the show.