Downton Abbey: The movie 'miracle'

Filming for the highly anticipated film, due out later this year, finally got underway last September, three years after the hit ITV show ended. Producers had a mammoth task juggling the cast’s conflicting schedules because the success of the period drama meant the actors are in demand. “There was always talk about us doing a movie,” said 55-year-old Bonneville, who plays the family patriarch Robert Crawley, Earl of Grantham.

“There were a couple of situations with the script and we were all in different places across the world.

“When we all got back together in the summer I said, ‘It is a bit of a miracle that we are all here back together.’ It is rare. It won’t happen again.”

Downton’s creator Julian Fellowes previously said the greatest challenge for the project has been “rounding up the actors who have now gone off to the four corners of the Earth, in Hollywood, on Broadway, doing plays, doing series, and so on”.

But the film, which takes place in late 1927 more than a year and a half after the events depicted in the series finale, will see many of the original line-up return.

Michelle Dockery will reprise her role as Lady Mary Crawley alongside Laura Carmichael as Lady Edith, Elizabeth McGovern, who plays Bonneville’s on-screen wife Lady Cora, Dame Maggie Smith as the irrepressible Dowager Countess and Allen Leech as Tom Branson.

Bonneville added: “It was a marvellous experience and every department was absolutely at the peak of their game. It was a fantastic cast. The production vales were very high.

“It was great to be back. Some of the characters weren’t there as unfortunately they were not in the script. It was not that they turned it down.”

Cast members not returning include Ed Speelers as footman Jimmy Kent but perhaps the biggest absence is Lily James, who played Lady Rose before finding stardom in films such as Mamma Mia! Here We Go Again.

Downton Abbey, the film, is due for release in cinemas on September 13.