When butler Charles Carson retired from Downton Abbey due to ill health at the end of the final series, it was with great regret.

So when he is asked to return to duty for a royal visit in a new feature film of period drama, “nothing could be better than that for him”, according to actor Jim Carter.

“For Lady Mary to ask him to come back to serve the King and Queen, it was going burst his buttons,” says Jim.

The exchange is seen in the trailer for the film, written by creator Julian Fellowes.

Jim, 70, says he expects viewers to be thrilled with the finished product on the big screen.

“The trailer gives a fair indication of the film, the main incident is the arrival of the king and queen,” he says.

“Queen Mary and King George V come to Downton Abbey and there is all the drama, excitement and worry that entails.

“That is the main event but all the familiar characters are there and their foibles and their fears.

“It is similar to the TV series but it is blown up large. We have got the kings troupe coming through on the parade and a big, big ball sequence.

"For the fans I think they will be very happy. It is everything people like about Downton Abbey in a two-hour film.”

Asked if it was a one-off, Jim suggested that was unlikely.

“It’s a business and I don’t make these decisions but if the film makes an awful lot of money there will be pressure to do another one,” he says.

“If Julian is free to write it then they can put us back together. Never say never, anything is possible. But lets get this first one done and see how it goes.”

(Image: ITV)

Fans have been looking forward to the prospect of a Downton movie for years, and it was first discussed by cast members when they were still filming the sixth TV series in 2015.

Jim’s character, known simply as Carson, is adjusting to marriage to Mrs Hughes (Phyllis Logan) when he suffers a palsy and is forced to retire.

“Carson would have died in harness quite happily but because he picked up a condition he had to retire,” says Jim fondly.

He says he has noticed that he and Carson now have a few character similarities. “It is a fact of getting older that you get a bit more old fashioned,” he says.

“The hippy Jim Carter has been long buried in the past. I am not quite as befuddled by technology at Carson is but I am not as up to date as I should be.

"Social media would have freaked him out but I have nothing to do with that either. So Carson and I are as one on that one.”

Jim says playing Carson is the “biggest thing he has ever done”, but he is glad the role did not come too early in his career as he would have wondered what to do afterwards.

The actor tried his hand at all sorts of entertaining including magic and juggling with a US circus school in 1978, before settling on acting.

(Image: ITV)

He worked across the big and small screen from the late 70s until today, appearing in Cracker, The Singing Detective, Midsomer Murders and Cranford.

His films include The Madness Of King George, Shakespeare In Love and Brassed Off.

The Downton film was a family affair for Jim, as his wife Imelda Staunton is Lady Bagshaw.

The pair married in 1983 and have a daughter Bessie, who is also an actor.

But Jim says he and Imelda barely saw each other on set.

“We only filmed for three days together and one of those days we were separated by a field and a lot of horses, and then the other two days we were in a dining room and she was sitting down and not drinking much, so I didn’t even get to pour wine for her,” he says.

“We fell into separate stories really. It was nice on those few days to get into the car together and go off to work together though. She had a whale of a time, as did I, just on separate days.”

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Jim is promoting a Downton Abbey concert on Saturday in the grounds of Highclere Castle, where much of the series is filmed.

He is hosting as Carson and the music is performed by The Chamber Orchestra of London with the television show’s composer, John Lunn, on piano.

“It is sort of a musical recap of the series really,” says Jim. “I think the music is a big part of the success of the series. You think about the opening music over the titles and it screams to everyone it is nine o’clock on Sunday night, it is Downton Abbey really.”

While Carson may have retired once, Jim says there are no such thoughts in his mind.

“I’d just like to see the next one that rolls off the block,” he says, referring to TV or film scripts coming his way.

“I think ‘Does that look fun? Will I enjoy it?’ Right lets do it. The joy of acting is you never retire, you keep going as long as you can. We never quit as long as we can remember the lines and don’t bump into the furniture.”