You said once that you would never write about Katherine, the fifth wife. What changed your mind?

Because I was so sure that I was never going to tackle Katherine, she could serve as light entertainment for me when I was recovering from writing my last novel, The Queen’s Sorrow. I settled down for a little light reading about her, but within half an hour I realised I’d been missing a trick. I’d been thinking of her as a ‘silly little girl’ but she was clearly rather more complicated than that. And the shape of her story too: that’s a gift, for a novelist; that utterly unanticipated, precipitous fall.