Margot Robbie has reportedly been cast in the Working Title and Focus Features project, Mary Queen of Scots. However, the actress will not be taking on the title role, but will star as Mary's cousin and border enemy, Queen Elizabeth of England.

The 26-year-old will star along with Lovely Bones actress Saoirse Ronan who is set to play Mary Stuart in the Josie Rourke-led project. Variety reported that the film will showcase the rivalry between the two monarchs, the Scottish queen's efforts to take over Elizabeth's throne and her subsequent imprisonment and execution.

The project is being produced by Working Title's Tim Bevan, Eric Fellner and Liza Chasin, and if given the go-ahead, will film will begin filming later this year.

Robbie's career has been cruising upward following her critically acclaimed performance as Harley Quinn in Suicide Squad. She is currently starring in Goodbye Christopher Robin, a film about Winnie the Pooh author A A Milne, in which she plays his wife.

She is also set to star in the thriller Terminal which follows two assassins, a fatally ill teacher, an enigmatic janitor and a waitress with a double life, all of who's lives will unravel at the hands of a criminal mastermind.

Robbie also wrapped up production of I, Tonya, a film about ice skater Tonya Harding, in which she plays the lead.