With the fifth season of Downton Abbey due on screens later this year, the show's creator, Julian Fellowes, has said that the period drama is "not going to go on forever".
Fellowes has been commissioned to write a new US drama called The Gilded Age but told The Wall Street Journal that he would only begin work on it when Downton Abbey had come to an end.
He said of The Gilded Age: "I haven't written it yet, but it's about the old aristocracy, the Winthrops and the Stuyvesants and the new money of oil and gas and shipping in the 1870s. It will all be fiction - it won't be real people - but when those families descended on New York, they took over."
As to Downton Abbey's future, he said: "I don't know yet if there is a season six, but it's not going to go on forever. It won't be [US legal thriller series] Perry Mason."