"Downton Abbey" ending after season 6

It's official: The next season of "Downton Abbey" will be its last.

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 him 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.

It had been rumored for some time that "Downton" was going to come to an end after season 6, which is currently being filmed (the show even got a recent visit from real-life royalty when Kate, Duchess of Cambridge, visited the set and met the cast and crew).

Maggie Smith -- who plays the formidable Dowager Countess of Grantham -- seemed to confirm the end was near in a recent interview with the U.K.'s Sunday Times. "They say this is the last one, and I can't see how it could go on," the 80-year-old actress said, adding, "I mean, I certainly can't keep going... To my knowledge, [my character] must be 110 by now. We're into the late 1920s."

The acclaimed, beloved and awards-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 Smith, Hugh Bonneville, Jim Carter, Michelle Dockery and Elizabeth McGovern.

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.

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."