Downton Abbey executive producer Gareth Neame confirmed Thursday what we've all known: The upcoming sixth season will be the show's last. But why end it now?

"There's so many different explanations," Neame said on a conference call Thursday. "I think our theory is that it's good to quit while you're ahead. We feel the show is in incredibly strong shape. The scripts that we're working on for the upcoming season are fantastic. The show is so popular globally, but the danger with this sort of thing is to let them go on forever. The danger is that you run to seven, eight, nine, 10 years. ... But I think it's more important to us to make a perfectly formed show, in our opinion, that we bring to an end when we think the timing is right, and that people will love and remember that show for many, many years to come, and not feel that there was any sort of drop-off or we outstayed our welcome."

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Structurally, the sixth season will mirror the previous five, with nine hour-long episodes and a two-hour Christmas special for the finale.

Neame said that he and creator Julian Fellowes have been stunned by the show's success, especially in the States, and that the decision to wrap up after Season 6 was a joint one among Neame, Fellowes and the cast. "It would be very tempting, very easy, to go for another year or beyond that, but it doesn't feel right for any of us," he said.

Neither ITV in the U.K. nor PBS in the U.S. expressed a desire for the show to come to an end, he added, and a slight decline in ratings in the U.K. last season did not have an impact either. "There's no show on television that gets canceled because it has 10.5 million viewers," Neame pointed out.

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The producers "couldn't rule out" doing a spin-off, according to Neame, but there are no plans currently in place. A Downton Abbey movie, however, seems more promising. "We would be very interested in that. It is definitely something that we're contemplating," Neame said of a film adaptation. "But I can't confirm that it's definitely going to happen."

Neame wouldn't comment on any specific plot points for Season 6, but indicated that the narrative will give fans a sense of closure. "Right from the beginning of this show, we have been about the end of a way of life, the end of a particular era of history," he said. "The way of life that we depict that people so enjoy, the idea of the aristocracy and the extraordinary lives that they led, it was all coming to an end, and we've been talking about this through the episodes. ... So we will now in this final season be starting to see how that way of life comes to an end."

Are you disappointed Downton Abbey is ending? Do you want a movie or a spin-off?

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