NEW YORK - A grand manor will close its doors to millions of weekly guests after "Downton Abbey" concludes next year.

Producers of the popular British period drama on Thursday confirmed it will end after its sixth season, scheduled to air in the United States in early 2016. The series, which airs earlier in the U.K., will have its finale on Christmas Day, 2015.

"Our feeling is that it's good to quit while you're ahead," executive producer Gareth Neame said during a conference call. "We feel the show is in incredibly strong shape, the scripts that we're working on for the upcoming season are fantastic, and the show is so popular globally. But the danger with this sort of thing is to let it go on forever."

He said the decision to wrap was made by himself and Julian Fellowes (who created the series and has written every episode) in conjunction with the cast.

Asked about a rumored "Downton Abbey" feature film, Neame said, "It would be great fun to do," but added there so far are no plans in place, nor are there plans for a series spinoff.

The acclaimed, beloved and award-showered drama has tracked the fates of the aristocratic Crawley clan and their servants amid the social upheavals of pre-First World War Britain into the 1920s, as the characters of both upper and lower classes cope with their rapidly changing world.

Stars include Hugh Bonneville, Jim Carter, Michelle Dockery, Elizabeth McGovern and Maggie Smith.

The series premiered on the U.K.'s ITV network in 2010, and on PBS' "Masterpiece" anthology in early 2011, inspired in part by the 2001 Robert Altman film, "Gosford Park" (written by Fellowes), and presented as a variation on the British classic "Upstairs, Downstairs."

"Let's not forget," said Neame, "when we set out to do this in the first place, we thought we would have a good success in the U.K. and that very traditional outlets for British content globally would be there."

But almost instantly "Downton Abbey" took on a life of its own.

"We did not know we would be in 250 territories worldwide," Neame said. "We didn't know we would be one of the biggest shows on American television. We would have been perfectly happy for it to run for three seasons, then end it."

In the U.K., it became the highest-rating drama of the past decade, with an average of 11 million viewers over its five seasons.

Season 5, which concluded in the U.S. earlier this month, drew an average audience of 12.9 million viewers.

"Masterpiece" executive producer Rebecca Eaton called the series "a gift, a gift from the television gods."

She said it coincided with the 2009 rebranding of "Masterpiece," which, among many changes, led to dropping "Theatre" from its title.

"And along came 'Sherlock' and 'Downton' in the same season, and transformed us in many ways: Drawing a giant audience, a new audience, helping pull in an underwriter, solidify our position with stations and donors to the station," Eaton said in a phone interview. "Then we created the Masterpiece Trust. So, a complete game-changer."

"Downton" also benefited from the shift in how TV is consumed, including binge viewing and the growth of social media that turned watching telecasts into group experiences, she said.

She was optimistic about life after "Downton." She noted that "Poldark" and "Indian Summers," in the "Downton" mode of extended British series, are coming to "Masterpiece."

"'Indian Summers' is even sexier" than 'Downton,'" she said. "And 'Poldark' has a death and a birth and money, and all the things you would expect."

And, for one more turn, there's "Downton Abbey."

Production of the upcoming 13-hour season is well underway, Neame said, but he kept mum on any details apart from saying all the current characters would be back and be given satisfying resolutions.

"We very much have an eye to where the characters will end up," he said. "What will become of poor Edith? Will Anna and Bates ever get a break? People want to know these things!"

While Neame acknowledged the temptation to carry on such a breakout success indefinitely, the series, he said, "has always been viewed by everyone involved as a bespoke, well-crafted piece of popular television."

The decision to call it quits was reached through a process of many conversations. But having now made the decision official, Neame said, meant "a very emotional day for all of the people involved in the show."

Frazier Moore is a national television columnist for The Associated Press.