Behind the scenes at the play ‘Mary Stuart’

It’s a story of two Queens – one in prison, one on the throne. The play Mary Stuart tells the tale of Elizabeth the First and Mary, Queen of Scots and their intense, tortured rivalry. It stars Juliet Stevenson and Lia Williams, who share the roles of Mary and Elizabeth, flipping a coin in front of the audience every night to determine who will take on which role. I went to meet them and ask them about this unusual casting technique.