Right from the very beginning, I knew I wanted to write palpably Scottish fiction.

Witches never existed, except in people’s minds. All there was in the olden days was women and some men who believed in herbal cures and in folklore and in the wish to fly. Witches? We’re all witches in one way or another. Witches was the invention of mankind, son. We’re all witches beneath the skin.

I don't think I have one particular favourite writer. I have many whose works I will always buy or reread - Muriel Spark, Anthony Powell, Robert Louis Stevenson, Ruth Rendell, James Ellroy, William McIlvanney, Kate Atkinson, John Burnside, Louise Welsh, Iain Banks.

I'm interested in Scotland now and then, how it's changed. I want to get the reader to think about that by thinking about something from the past. How has society changed, how has policing changed, have we changed philosophically, psychologically, culturally, spiritually?

The most difficult part of any crime novel is the plotting. It all begins simply enough, but soon you're dealing with a multitude of linked characters, strands, themes and red herrings - and you need to try to control these unruly elements and weave them into a pattern.

A good album should be more than the sum of its parts.

You wouldn't think you could kill an ocean, would you? But we'll do it one day. That's how negligent we are.