So we got a scene from outside history – unknowable.” Nathaniel Parker, who returns to the role of King Henry VIII, also left a mark on the page.

I said, ‘No, it’s a cellar where he killed someone.’ And it began to fall into place.

Mantel adds: “Ben said that he kept having, on stage, the memory of being under something like a bridge or an arch. There was a moment when Cromwell was interviewing Francis Weston in the Tower and the actor playing Weston put in a detail of his legs shaking with fear and I felt that reminded Cromwell of something. “I’d have Cromwell thoughts and insights on stage,” says Miles, “and would email Hilary on my way home. They had already, in a sense, collaborated on the third novel, as performances of the first two plays became a sort of workshop for the final book. She said it was a great idea and she should have thought of it.” So I had a think, then emailed her to say I’d really like to have a go myself. During a rehearsal break, Miles recalls: “Hilary asked me if I knew of any writers who might be available. With Mantel unable to work with Poulton on what the company calls “play three”, she was wary of going alone. I don’t want to be a Tudor talking head for ever’ … Hilary Mantel. The voices – the way actors play off each other – can make you see the need for a bit more, a bit less, here and there.” Obviously, you anticipate as much as you can, but there’s a lot of fixing in the room. These sudden callouts are, says Mantel, “the exhilaration of the process.

Our scheduled interview was politely delayed because the director, Jeremy Herrin, needed Mantel in rehearsals (she attends most days) to answer questions from the cast about historical context and supervise the insertion of rewrites, an example of the emergency plumbing aspect of being a dramatist that distinguishes it from the slow isolation of book-writing, where novelists make changes, for themselves or editors, over years or months. But I don’t see the plays as deriving from the novels but as things in themselves.” But theatre is where I should have been, I think.” She doesn’t regret the novels? “No. The novel is a good form for someone who only has pencil and paper. And when I started I had no literary resources and no contacts. But if you’ve got poor health, as I’ve had, it’s hard to work in a team. On reflection, I’ve always known it: I’m devoted to the theatre. “That awful self-consciousness that beset me all my life just left me. “It surprised me, when we did the first plays, how comfortable I was in a rehearsal room,” she says.

Hilary mantel the mirror and the light