The subject is “Downton Abbey,” probably the most popular television series yet produced by the Brits. It plays here as Masterpiece Theatre on PBS, which no doubt is the reason about half the people I survey reply, “Huh?” PBS has long been considered a sidetrack to check for something to watch when there’s no game on, or no “Sopranos” or “Simpsons.” I dare say that almost no one switches to it from Fox News. It airs a few popular shows: “Antiques Road Show” is well enough known that Geico has lampooned it in an insurance ad. Agatha Christie’s Hercule Poirot and Miss Marple are pleasantly relaxing, with unsurprising denouements. The new incarnation of Sherlock Holmes, a hyperactive, fruitcake genius with a cellphone, is borderline.

Beneath the borderline is “Keeping Up Appearances” (a tedious joke told over and over and rescued only by the manic activity of its protagonist, Hyacinth Bucket, who insists it’s pronounced “BooKAY”). It’s better than a basketball game; “As Time Goes By,” though fronted by Dame Judi Dench, is not. Then there’s a wasteland of concerts by long-ago groups from the Belmonts to Roy Orbison to Peter, Paul, and Mary. Don’t get me started on André Rieu or Tony Bennett, whose greatest achievements are appearing to fill the large concert halls in which they perform.

Public Broadcasting, which has seemed to suffer from a case of pusillanimity since the attacks of the conservative right began to affect its funding, has, with “Downton Abbey,” finally replied with a broadside. American viewers watch it at dedicated parties complete with Edwardian high tea and desserts. Web sites argue about the future of Lady Mary and Matthew Crawley, whose star-crossed, faltering relationship is so frustrating that I have occasionally found myself shouting at the screen, “Kiss her, you ass!” Patricia Morrison, widow of rocker Jim Morrison, reportedly watches “Abbey” in bed, clad in a sweat suit and tiara. Facebook pages encourage readers to answer the question, “Which character in ‘Downton Abbey’ are you?”

As with most period productions, I love the cars. The Crawley family seems to putter along with what looks like a 1911 Renault Landau; but a visiting general shows up for dinner in a fantastic 1910 Rolls-Royce Silver Ghost Torpedo Tourer! Lots of Model T Fords, which is authentic for England at the time; but auto aficionados have pointed out that the painted-radiator models used in the production weren’t being manufactured till after that period.

It’s not just cars that careful watchers pick up on. When Cora, Lady Grantham, miscarries what would have been the heir to the estate (an accident engineered by her Iagolike maid, O’Brien), the evil footman, Thomas, wonders aloud down in the kitchen what all the fuss is about. “It’s wasn’t any bigger than a hamster,” he says. Several attentive Brits noted that hamsters weren’t introduced to England till after the First World War. When Matthew Crawley appeared pudgy in his army uniform, a blizzard of tweets motivated him to lose about 20 pounds. This is the kind of problem producers and actors love: People are watching!

Generally, I consider soap operas to be on a par with parking tickets or a case of shingles. Shot almost entirely indoors in generic rooms, they feature characters with no visible means of support, no jobs to go to, no kids to be changed or fed, and an inordinate, gossipy interest in the personal lives of other people no more significant than themselves. The scenes are brief and disjointed, so that no actor has to memorize more than a few lines at a time. The dregs of drama, I call them, but I guess they do sell soap and Swiffers. I wonder if there’s any crossover: Do fans of “Days of Our Lives,” for example, get excited about “Downton Abbey”?

The Crawley “great house” is a huge hotbed of personalities and intrigue with its lid kept firmly on by centuries of class distinctions. The Dowager Countess Violet, played by Dame Maggie Smith (whose zingers steal almost every scene in which she appears), embodies the traditional disdain of the upper classes for the lower. She fears that the war, with its leveling influence, will soon have titled people marrying chimney sweeps. Yet she, along with a few others who initially seem locked into disagreeable personae, shows occasional warm flashes of humor and humanity. O’Brien, Lady Cora’s maid, whose default mode is a simmering desire for revenge, occasionally is forced to confront her meanness by the generous people around her, both upstairs and down. Thomas, a truly nasty and bullying brute whose rage is stoked by his sense of low station and his homosexuality (which cannot be expressed except surreptitiously), seems at this stage in the series to be irredeemable. But ever the optimist, I have hope for him.

If you’re one of the people who answer, “Huh?” to my question, this is all gibberish to you. You’d have no appreciation of the anguish of Mr. Bates, Lord Crawley’s valet, and the housemaid Anna, whose true love is thwarted again and again by Bates’ vengeful first wife; or the disillusion of Branson, the IRA chauffeur, when he learns his revered Bolsheviks have slaughtered the Tsar and his family; or the jealousy of Edith, who feels she can’t hold a candle to her beautiful older sister, Mary; or the equable and absolutely steady butler, Carson, whose “Hmm...”, varying from ironic to disapproving, has given me a brand-new tool of expression. If you haven’t caught it yet, it all starts with the sinking of the Titanic. And it’s not too late to get aboard!