David Tennant has joined the cast of 'Mary, Queen of Scots'.

The former 'Doctor Who' actor's role is yet to be revealed, but he joins Dunkirk's Jack Lowden, Guy Pearce, Martin Compston, Joe Alwyn and Downton Abbey's Brendan Coyle in the forthcoming drama.

Margot Robbie is set to portray Queen Elizabeth I, who died in 1603, opposite Saoirse Ronan as the titular character.

The big screen project, which is being directed by Josie Rourke and is expected to go into production this year, is based on the true story of Mary Stuart's attempt to overthrow her cousin Elizabeth's seat on the English throne, which, ultimately, led to her being condemned to years in prison before facing execution.

Filming has begun in England and Scotland on the Working Title Films production.

The feature film is being produced by Tim Bevan, Eric Fellner and Debra Hayward.

Academy Award-nominee Beau Willimon has penned the script which is adaptation of John Guy's biography 'My Heart is My Own: The Life of Mary Queen of Scots'.

The movie is expected to be released next year.

The chairman of Focus, who own worldwide rights and will release the movie in the US, Peter Kujawski said: "We are privileged to be collaborating with our partners at Working Title on this stellar production, and with Josie as she makes the exciting move from stage to screen work. With two of today's most vital actresses bringing to life two female titans, 'Mary, Queen of Scots' will be one of the movie events of 2018."