A book must have moral purpose to be any good. Why, I don't know.
Romantic love, or sex, is the only good thing in a life that is being lived in a dark way.
For John le Carre, it was always who's betraying who: the hall-of-mirrors kind of thing. When you go back to the '30s, it's a case of good vs. evil, and no kidding. When I have a hero who believes France and Britain are on the right side, a reader is not going to question that.
I am there to entertain. I call my work high escape fiction; it's high, it's good - but it's escape, and I have no delusions about that. I have no ambition to be a serious writer, whatever that means.
What you get in the Cold War is 'the wilderness of mirrors' where you have to figure out what's good and what's evil. That's good for John le Carre, but not me.
When I read period material - and it ain't on Google - I am always alert for that one incredible detail. I'll read a whole book and get three words out of it, but they'll be three really good words.
Yes, I'm a reasonably good self-taught historian of the 1930s and '40s. I've never wanted to write about another time or place. I wouldn't know what to say about contemporary society.