From a New Zealand newspaper's Q & A with Ian Rankin, who's currently bigging up the excellent 'The Impossible Dead':
The book that changed me is
... Laidlaw by William McIlvanney. I read this in the early 1980s when I was a student but also trying to become a published novelist. It's beautifully written, with taut plotting and a clean style. Laidlaw made me think I could maybe write my own crime fiction.
It has to be said . . . Morris Cafferty is no John Rhodes.