Downton Abbey is so popular in the US that it has broken a ratings record with the first episode of series four.

The hit ITV period drama screens on PBS in America and has become the broadcaster’s highest-rated drama debut in its history, with the opening episode of the new season.

According to The Wrap, an average audience of 10.2 million viewers tuned in, which boasted a 6.2 household rating – a 22 per cent improvement from last year, which opened to a 5.1 rating and 7.9 million viewers.

PBS president and CEO Paula Kerger said: “As this captivating drama continues, our audiences have been eagerly awaiting this new season to see what’s next for these beloved characters.

“I’m so pleased that millions of viewers have returned to Downton Abbey on their local PBS stations for what has become a post-holiday tradition.”

Dan Stevens, who played Matthew Crawley in the series until he was killed off on Christmas Day 2012, said recently that he planned to keep up with the drama from his new home in America.

He told The Hollywood Reporter: “I have absolutely no idea what becomes of Mary because I want to watch it with the American audience.

“It will be fun. After all, I live in Brooklyn now.”