"I don't think people talk to each other in relationships," says Sadie Jones. She's referring to the stiff-upper-lip, post-war society of the 1950s where her new book is set, but she could just as easily be talking about today. The best-selling author, sitting comfortably in her West London home, suddenly becomes animated.
"The overwhelming need to write Small Wars came out of feeling so upset by these terrible repetitive histories, the way we don't seem to learn. It makes me really angry." There's a venom in her voice, which is not what I'd expected from one of the most affable, friendly British writers you could expect to meet. But just as her first book, The Outcast, had a literary ambition beyond a summer read (although it appeared on various summer reading lists), Small Wars is so much more than the portrait of a marriage under pressure. Those elements exist but the central character, Hal Treherne, is enigmatic, a soldier whose emotions and morals start to fall apart when he's posted with his wife, Clara, and small twins to Cyprus in 1956 to defend the British colony in turmoil. He sees things no one should have to see but, at first, is glad of the "action". Clara, meanwhile, imagines things no one should have to imagine.
As Hal wrestles with the implications of duty, Jones skilfully weaves in war, relationships, the male psyche and an overriding sense of a man battling with his conscience. "But with all those elements it was a bit like plate spinning, and, initially at least, I was very wary of going back to the 1950s again," she says. "That's obviously where The Outcast was set, and you really don't want to be pigeonholed. I wanted to kill everyone who made these jokes to me about the 'difficult second book'."
There must have been a pressure, though, in following up such a successful book, a worry that perhaps The Outcast might have been a delicious one-off. It had, after all, taken her 15 years of largely unsuccessful script, film and play writing to get to this point. "All the elements I wanted to get in made the actual writing of it really difficult," she remembers. "But it wasn't until the very end that I felt any of the pressure that comes with telling a story that perhaps people would be anticipating. The relief when I could make it clear that even though we were back in the 1950s, it wasn't just the same book, was immense."
So why go back to that era at all? Hadn't she said everything she wanted to say about love and shame in that time in The Outcast? "I know, I did feel that," she says. "But when I discovered Cyprus I became completely obsessed by it, and I knew that was the story I wanted to tell because of its similarities to what's happening now in Afghanistan. It had to be where it was. Initially it was the logistics of the actual soldiering that interested me. That there could be, like Afghanistan, these quite small skirmishes where, nevertheless, lives are lost. The two countries even look a bit like each other."
She slowly began to realise that Cyprus could be a way of exploring events in Afghanistan without having to get into the specifics of an ongoing conflict. It was a while, though, before she found her lead character. She remembers the moment quite clearly: when she read about Flt Lt Malcolm Kendall-Smith, a British medical officer who was jailed in 2006 for opposing the war in Iraq. What's slightly strange, then, is that Hal is the opposite of Kendall-Smith. Where the real-life officer was prepared to take a stand and go public for his principles, Hal cannot. His sense of duty to his country prevents him from fully revealing the cover-up that is at the centre of the book. He hears about the shocking, vengeful attack on two women in Limassol by the men under his command and it changes him: he condemns the assault but in a sense it condemns him, too. He becomes a haunted man, tragically distant from the wife who loves him - and violent towards her as well.
In her research for the book, Jones met many soldiers who had been to war. "All the ethics, the accusation and counter accusation and the treatment of prisoners, all of that came up. So it was just the perfect place for me to discuss the real point, that this kind of appalling behaviour is universal in conflict." The line in the book that emphasises this - "the outrage of the collective frees the individual to commit terrible acts" - is uncharacteristically clunky amid her usual, beautifully flowing prose, but it's a point worth making.
"There's supposed to be this battle for hearts and minds but in that situation, people can easily become dehumanised. What's very sad is that we're herd animals and we respond to whatever the collective behaviour is - and you can take that right back to Nazi Germany. We all like to think that we would be the person who stands up and says: 'No, this isn't right.' But what interests me is this overwhelming human urge to join in and be like other people."
The character that best represents Jones's message is not Hal at all, but a timid interpreter called Davis. He witnesses the abuse and, when he decides to report it, it seems Small Wars will surely take a different tack, perhaps becoming a moral tale of the little guy standing up for what's right. But in the end he's a coward - and for Jones that's the sad fact of life. "In a culture where people are doing wicked things, people who aren't wicked themselves tend to go along with it," she says.
For all the talk of wicked deeds, Jones is just as keen to talk about the emotional power of Small Wars as discuss the political subtexts behind it. After all, this is a book that is as much about Hal's wife battling her fear of the unknown and the crushing boredom of domesticity. It's not so much a dark tale as a very ambitious undertaking, one that's just as happy to speak of the unfettered joy of eating strawberries in the sun, or of how a blazingly bright Cypriot beach can spark happy memories of Cornwall. Hal's eventual reconciliation with Clara is dubious. The reader not actually sure whether it is a reconciliation.
"That's really what I mean when I say people don't talk in relationships," Jones says. "Hal and Clara's relationship is crippled by them not being able to talk to each other. You'd imagine all he would need to do is tell her why he's acting the way he's acting and she'd understand, but he doesn't function like that. We might act and speak differently now, but you have to admit you'd prefer to avoid confrontation in a relationship if possible. And I don't think you'd find an army wife now who would say to her husband: 'I'm so frightened. I need to talk about this.' I just don't think people do that."
All of this might suggest that Jones wasn't writing about the 1950s at all when she chose her setting for Small Wars. She was born in 1967. Her experience of the 1950s extends to writing one well-received novel set during that period and enjoying the first series of Mad Men. But, for her, the connections across the decades are relevant. "I am fascinated by the male condition - how men behave in society, what their responsibilities are," she says. "What I do know about the 1950s is there was a gender pressure of sorts in that men had such a clear role. They were the providers, these impressive adults. Now that role has been taken away in many parts of the world. The 1950s men I have written about in both The Outcast and Small Wars have their roles taken away from them, too. In The Outcast, they come back from the war and have to deal with not quite fitting in. And what happens to Hal, well-"
Jones trails off, and it's not just because she doesn't want to give away the ending. You sense she feels a deep sympathy and connection with her central character. "I knew what was going to happen because that's the way I write, but I was so upset I almost changed it," she laughs. "Of course, I couldn't do that because I was absolutely determined not to have a war as a subplot to a romantic story. In my view, that's a despicable thing to do. But I do catch myself wondering whether he and Clara will be all right. I think they will."
Small Wars reveals that The Outcast wasn't a one-off - it may have taken Jones some years to get to this point, but she's now arrived as one of those rare writers who can sell thousands of books but please the literary critics, too. So it is rather ironic that she's currently working on the film adaptation of The Outcast after all those years of struggling with screenplays. "I've written it," she says. "We've got a director. I'm not counting my chickens but we've made a good start."
I ask her if it feels odd to be going back to that world after finally making it as an author. "Well, kind of. Books give you more space, and you can do whatever you like with your imagination, which is great, but that has its own pressures, in a way. But being able to describe things, which you can't really do in screenplays, is really lovely. It's like being let off the leash."
Small Wars (Chatto & Windus) is out now.