It's a tough question to answer because the ideas come in different ways - from talking to people, from reading newspapers, from watching TV.
But my eighth novel - The Double Tap - came to me all at once. I was flying from London to Baltimore and while I was on the plane I got the whole idea, characters, set-up and plot twists. Everything. And the book is pretty much as I envisaged it on that seven hour flight.
The one thing that did change was the title. I originally wanted to call it The Judas Goat but during the course of the writing I realised that the title wasn't edgy enough.
It's the third book to feature former SAS sergeant Mike Cramer. Cramer was a terrific character and I do regret killing him off. It would have been great to have had three continuing Stephen Leather characters - Dan "Spider" Shepherd, Jack Nightingale and Mike Cramer. But it wasn't to be - the set up of The Double Tap really didn't leave me a way out and Cramer had to die.
The story is about a serial killer who is a professional assassin - an assassin who always kills close up with two shots (hence the title). The powers that be discover who is next victim is to be and persuade Mike Cramer to take his place even though it's effectively a suicide mission.
The book has had several covers over its life and to be honest I have never really been happy with any of them.
These days The Double Tap sells more as an eBook than a paperback so I guess the cover isn't as important as it used to be in the days when all sales were through bookshops and you needed shelf appeal to sell.
I do sometimes think about revisiting the Mike Cramer character. There's no getting away from the fact that Cramer is dead, but I could well do a novel or two from his SAS days. I just wish there were more hours in the day!