From PEOPLE Magazine Click to enlarge
Last May, stars from Gwyneth Paltrow to Beyoncé slipped into their finest couture for the Met Gala in New York City-but inside the A-list party, everyone was clamoring to talk to two women who, just a year and a half earlier, were largely unknown: Downton Abbey stars Michelle Dockery and Laura Carmichael. "We were blown away," recalls Carmichael, who stars as Edith Crawley in the hit PBS Masterpiece series about the aristocratic Grantham family and their servants in early 20th-century Britain. (Dockery stars as her sister Mary.) "Brooke Shields, Martha Stewart-all these people were saying how much they enjoyed our show. It's surreal!"

Now Downton mania has gone nationwide. After earning 16 Emmy nominations (and three wins) for its second season, Downton Abbey officially became a phenomenon on Jan. 6 when its third season premiered to 7.9 million viewers-nearly doubling last year's audience and giving PBS its highest ratings since 1997. (In the U.K., where the show airs first, 9.7 million tuned in last fall.) Why has a show so rooted in the past struck such a modern chord? Executive producer Rebecca Eaton has a theory: "It's a family saga, and now our communities are so fragmented. I think we yearn to be in a place like Downton Abbey, all together."

She could very well be talking about life on location. The cast and crew log 12-hour days at Highclere Castle (see box) and London's Ealing Studios during the six-month-long shoots, often helping each other with crossword puzzles during downtime and meeting up at their hotel after work. "We really are very close," says Carmichael. "It's a treat." Well, not all of the time, thanks to creator Julian Fellowes's dogged quest for historical accuracy. "If you get it all correct, there comes a sense of it being believable," says Fellowes. That means period-appropriate food, social customs and clothing, much to the actors' chagrin: "They don't like wearing the corsets, which are part and parcel. And the men are all wearing wing collars, which cut into their necks," says executive producer Gareth Neame. "But we try to get it right."

As season 3 draws to a close (the finale airs Feb. 17 on PBS, but those who can't wait that long will be able to purchase the season on DVD or download it on Jan. 29), the creators are already gearing up for what comes next; filming resumes in February. Not everyone in the cast makes it to season 4, which Fellowes says will pick up just six months later. "Exits can be good opportunities for drama because they allow you to take the story in a different direction," teases Neame, who adds that there's plenty of story left to tell: "I think we have life beyond the fourth season!" In other words, the latest British Invasion has only just begun.

  • Contributors:
  • Additional reporting by Simon Perry,
  • Liz Corcoran.