Maggie Smith was the last original cast member to join 'Downton Abbey' film

Bringing the main cast of "Downton Abbey" for the big screen reboot was a mammoth task and veteran actor Maggie Smith was the last original cast member from the Emmy-winning series to sign on for the film.

Executive producer Gareth Neame has revealed that Smith, who reprises her role of Violet Crawley, the Dowager Countess of Grantham in the movie, didn't give a nod till she was sure everyone was returning for the film.

"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," Neame told Deadline.

Hugh Bonneville, who plays Robert Crawley, Earl of Grantham in the film, said the biggest testament to the film was 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," Bonneville added.

Also returning for the film are series regulars Michelle Dockery, Laura Carmichael, Elizabeth McGovern, Allen Leech, Matthew Goode, Joanne Froggatt , Brendan Coyle, Robert James-Collier, Lesley Nicol, Sophie McShera, Phyllis Logan, Raquel Cassidy and Michael C Fox.

The British period drama is directed by Michael Engler, from series creator Julian Fellowes' script.