For many people you are the political journalist Jonathan Freedland, who writes for The Guardian and The New York Times and is heard on the radio. But in your other life you are Sam Bourne, thriller writer. What first got you interested in writing thrillers?

The very first story idea I had, which had been germinating in me for decades, was a thriller. There was no getting away from it. That became The Righteous Men which was my first Sam Bourne book. So in a way, once I had the idea for that first story any decision about genre was taken, because the plot was born to be a thriller.

So how would you define a thriller? What made the book so definitely of that genre?

I don’t often get asked that question or even think about it, but I would say that you need a protagonist who is somehow in peril – who is pushed into such an extreme situation that they are willing either to kill or to risk being killed. So the stakes are extremely high and there is some urgency involved. Obviously all these rules are made to be broken. Certainly in the thrillers that I read there is something larger than the protagonist at stake. For me, the ones that are interesting are those where the other thing in play is something beyond that individual – something in the world, either politics or history – which raises the stakes.

That notion of something bigger than the protagonist is very much a part of your own thrillers.

That is the ambition of my books – to be about something beyond the immediate domestic drama of the main character.

What made you decide to use a pseudonym for your thrillers?

It was really a decision taken for me, by my agent and publisher. They both felt there was value in distinguishing my daily job as a Guardian columnist from the fiction I was writing. The thinking behind it was that I write quite a polemical, opinionated column, so it would be a pity if disagreement with the ideas I am advancing in that column would somehow deter people from reading my novels.

There was also a commercial decision involved. My agent said that my real name – Jonathan Freedland – sounds like “a pointy headed columnist for a pointy headed newspaper”! That was not quite the brand he wanted. Sam Bourne was seen as a much better name for a thriller writer. And it was good to be given a fresh start, because as Jonathan Freedland I had written two books of quite serious non-fiction. That was seen as something that might confuse potential readers.

Did you find it liberating to write under a different name?

I did. I think there would have been a self-consciousness about writing fiction, about feelings that are personal and intimate, under the same name and the same voice as what I do during the week – writing a column about things like David Cameron, the coalition and foreign policy. Writing under a different name, I didn’t have to think about my column and maintain any kind of consistency between the two.

But one never fully escapes that internally. For example my second novel, The Last Testament, is set in the Middle East. The central character is a peace negotiator between Israelis and Palestinians, and that is an area I write about a lot as a journalist. It would be very constraining to feel that I had to maintain a consistent line politically between what I argue in the column and what is advanced in the novel.

But it must have helped with your research.

Yes, there are many positives of this double life. Jonathan Freedland the journalist is a conveyor belt of ideas and stories to Sam Bourne the novelist. That is the huge advantage. In my latest book, Pantheon, that worked absolutely directly, in the sense that the germ for the story came from a chance remark by the former [British] cabinet minister James Purnell. He and I were having dinner a few months after his resignation, and he happened to mention one thing which planted the seed in my mind that turned into Pantheon.

What was that seed?

We came across the realisation, as you do in conversation, that we had a mutual friend. He said, “You do know the amazing story, don’t you, about his mother?” And I said, no I didn’t. So he told me that she was one of the child evacuees from Oxford to Yale in 1940, and had always suspected there was something beyond the original explanation for her evacuation.

And this forms the mystery at the heart of Pantheon, about what was actually going on with those evacuees.

Yes, and I am not sure how much to give away. I think that people might be drawn to the story because there is an element of eugenics. This idea, that we would now recoil from, was absolutely mainstream in both Britain and America in the pre-war period. In Britain it was going on in very surprising places, among luminaries of the left. And in America it took particular root in the university sphere. To complete the connection there was – and is – a suspicion that there may have been some of that involved in the motivation for the Oxford-Yale evacuation. But I don’t want to spoil the story. The good thing is, you still need to read it to understand how it all hangs together.