Reading can help prisoners to 'walk in someone else's shoes', says Mick Herron

Mick Herron steps into the daylight beyond the imposing main entrance of HMP Bullingdon in Oxfordshire and breathes deeply. The spy writing superstar had been addressing a reading workshop for some 35 inmates at the Category B prison, sharing the story behind his globally successful Slow Horses series, adapted for the television starring Gary Oldman as larger-than-life spymaster Jackson Lamb.