The announcement from Focus Features does note “the original principal cast” from the show will be back for the big screen production.
Brian Percival is also returning to Downton Abbey to direct; he has already spent time behind the camera for the show’s pilot.
In addition, we do know that Gareth Neame, Julian Fellowes and Liz Trubridge will produce, and Fellowes has already written a script for the project.
It’s still early days on the upcoming film project, so we don’t know exactly when the movie will be released, yet, but shooting will happen this summer.