After such a long journey, in which he has practically grown up with Slave Play, Harris’s undimmed enthusiasm about the play is noticeable, as if it has only deepened the role theatre plays in all aspects of his life. ‘Theatre is my religion,’ he tells me. ‘Growing up I read so many plays. And now, like some monk, writing plays for me is like writing little prayers to myself. And not everyone’s invited into my prayer. But much like you can read, say, Thomas Aquinas, that’s hopefully what is happening with people who engage with my work.’