Every time Stuart veered into self-pity or self-justification, she felt her hackles start to rise. She could have pointed out, and very nearly did, that it was his decision to screw Imogen Conrad rather than their exploitation of it that had ruined their lives, but what was the point? It made her sound and feel shrewish and embittered, and it was a train of thought and emotion she was trying to choke off.

Instead, she tried to make sense of what he had said. It occurred to her that Stuart might indeed have been a box-ticking exercise or, more worryingly, a red herring to disguise a much more important agent somewhere in Whitehall or perhaps even MI6. So perhaps Stuart had really not been Viper, after all.

Which meant, of course, that Viper was still active.

How easy it was for Moscow to throw Stuart to the wolves when suspicions started to sink in that there was a mole somewhere in the system.

But even this train of thought rested on a basic premise: that Stuart was telling the truth.

‘Did you mean what you said,’ he asked, ‘or was it just a trick to get more information out of me? I wouldn’t blame you if that was the case. I deserve it. But it would help to know.’

There was a long silence. Kate had to suppress another deep craving for a cigarette as she watched the young girl behind the counter light one and suck the smoke deep into her lungs before blowing it towards the blackened ceiling. The lorry driver had disappeared, apparently to the toilet. ‘I did mean it. In a curious way, despite the awful circumstances, these few hours we’ve spent together have been the greatest peace I’ve known since the day you left.’

‘For me, too.’

‘But I can’t change the fact that you wounded me deeply. The trust we had, the unique bond, is broken. For ever. We can’t repair that. So, in truth, I don’t know what I want. I miss you. I miss what we had.’

‘My sparkling wit.’ He was smiling at her.

‘Everything but that. So I . . . don’t know. I’m opening the door. Partly for the kids’ sake. I’m not certain that I’ll ever be able to walk through it. I can’t give you any promises. Perhaps we can find a way back to friendship. I’d hope that was possible. I don’t want to hate you. I don’t want the children to have that bitterness and rancour in their lives. But as to whether something more than that ever develops, I really can’t—’

‘That’s enough for now. I don’t want to push it.’ He put his palm over hers. ‘I know it’s going to take a long time.’