Dame Maggie Smith was the final 'Downton Abbey' star to sign up for the movie.
Dame Maggie Smith
Gareth Neame, the film's executive producer, has revealed the 84-year-old actress - who portrays Violet Crawley, the Dowager Countess of Grantham - waited until she was "completely sure everyone was going to do it" before committing to the project.
He said: "I suspect in a lot of ways, Maggie missed working with the other actors.
"When she was completely sure everyone was going to do it and it was happening, then she was on board."
And Hugh Bonneville - who stars as Robert Crawley, Earl of Grantham - has admitted there were "some hurdles" in getting everyone on board for the movie, but he is delighted the TV series cast reunited for the film.
Speaking to Parade magazine, he added: "The biggest testament to the film is that everyone turned up to play.
"We had some hurdles getting everyone in the same place at the same time, but there was a will to do it."
Other stars who will reprise their roles for the big screen version include Michelle Dockery (Lady Mary Crawley), Laura Carmichael (Lady Edith Crawley), Elizabeth McGovern (Cora Crawley, Countess of Grantham), Allen Leech (Tom Branson), Joanne Froggatt (Anna Bates), Brendan Coyle (Mr. Bates) and Matthew Goode (Henry Talbot).
But one star who won't be returning to the movie is Sue Johnston as the actress - who portrayed Gladys Denker in the TV series - revealed last week her character has been dropped from the film.
She said: "Denker was the first in the script and then the script disappeared. Imagine how I felt!"
Tagged in Hugh Bonneville Michelle Dockery