We novelists are frequently told that our characters must be sympathetic, and indeed it’s a risk for any writer to create someone like Anthony, who at the outset is smug and snobbish, with his strong sense of entitlement, if not of superiority. One could easily dislike him, as do some of his fellow-prisoners and – more so – some of the prison staff. But my challenge was to show him changing, broadening his outlook, growing in human sympathy and understanding. His relationship with Darren is crucial in this respect, yet I never planned Darren – he just turned up on the page one day and continued to develop and surprise me. That’s how my novels seem to work. I may begin with a detailed plan and outline, but then random factors sneak their way into the narrative and take the book in a new direction. Only by the time I wrote the last sentence, did I realize that Darren had been essential all along, especially as the nearest Anthony will probably ever have to a son.