I guess a lot of police keep their sanity by developing black humour.

Every profession has its own culture, but the police look at the world differently to everybody else. I call it a 'healthy culture of suspicion'.

My day starts with Radio 4's Today live or 'listen again' wherever I am in the world, thanks to digital radio - I even have an app on my iPhone that receives it.

Police do get obsessed with solving crimes. You know, particularly if there's been a murder, it becomes personal for the police officer very quickly, and it gets to the family. Even after they've retired, they carry on, not letting go.

Every novel starts with a theme, and I am constantly looking for big ideas.

There's a really classic cliche every time you switch the TV on - you see cops arguing. I have spent a day a week for many years in the presence of police and I have never seen them argue. It's a military hierarchy. They do what they're told. There's no bickering.

There are people who can achieve huge success in life, while adding a bit of fun and a splash of colour to this increasingly grey world.