Kell felt a quick burst of irritation at her easy assumption of American guilt. He wondered if Elsa had worked on the case in some capacity or had merely read about it in the European press.

‘Let’s just say that the Yanks were tough on him,’ he said. ‘We all were.’

‘What does that mean?’

Kell shifted in his seat, choosing his words carefully.

‘It means that we were a long way from home. It means that we were trying to break up terrorist cells in the UK and US. We felt that Yassin knew things that would be useful to us and we ran out of patience with him when he wouldn’t talk.’ Kell found himself coughing. ‘Eventually certain individuals became aggressive.’ He composed himself, still protecting the identities of American colleagues who had stepped over the line. ‘Did I physically touch him? No. Did I push him around? No, absolutely not. Did I threaten to get to his family in Leeds? At no point.’

Elsa did not visibly react. Her face was still as she said:

‘So the interview was as they described it?’ It was as though she had stopped herself using the word ‘torture’, like somebody stepping around a puddle. ‘What happened, Tom?’

Kell looked up. She was no longer serving the food, as if the meal was being held in quarantine. She was not judging him. Not yet. But she wanted to hear his answer.

‘You’re asking a man you’re about to sit down and eat supper with if he water-boarded a suspect? If I pulled out a man’s fingernails?’

‘Did you?’

Kell felt all of the despair of his final weeks at Vauxhall Cross rushing up to confront him.

‘Do you think I would be capable of that?’

‘I think we are all of us capable of doing anything.’

Yet the tone of Elsa’s reply implied that she trusted Kell to have behaved within the law and within the boundaries of his own decency. He felt a great affection for her at this moment, because such an accommodation was more than Claire had ever been able to provide for him. At times in the preceding months, turned out of SIS in quiet disgrace, he had felt like a criminal; at others, like the only man in England capable of understanding the true nature of the threat from men like Yassin Gharani.

‘I did not torture him,’ he said. ‘SIS does not torture people. Officers from both services do not break the codes of conduct with which they are issued whenever they go into …’

‘You sound like a lawyer.’ Elsa opened a window, an airlock being cleared. ‘So what’s the problem?’

‘The problem is the relationship with the Americans, the problem is the press and the problem is the law. Somewhere between those three points you have spies trying to do their job with one hand tied behind their backs. The media in London took the line that Yassin was a British national, innocent until proven guilty, who was tortured by Bush and Cheney, then flown to Guantanamo and stripped of his dignity. Habeas corpus. They charged that MI6 turned a blind eye to what went on.’

‘What’s your view on that? Did you ask where they were taking Yassin? Were you concerned about his condition?’

Kell felt the flutter of guilt, the shame of his own moral neglect, yet the certainty that he would not now act differently. ‘No. And no.’

Elsa looked up and met his eyes. Kell remembered the cell in Kabul. He remembered the stink and the sweat of the room, the wretchedness on Yassin’s face, his own lust for information and his contempt for everything that Yassin stood for. Kell’s zeal had obscured even the slight possibility that the young man in front of him, starved of sleep and care, was anything other than a brainwashed jihadi.

‘What I did, what several intelligence officers did, what was wrong in the eyes of the law and in the eyes of the press, was to allow others to behave in a way that was not in keeping with our own values. They found words for what we were accused of doing. “Passive rendition”; “Outsourced torture”. This has always been the British way, they said, since imperial times. Get others to do your dirty work for you.’ Elsa placed two pieces of kitchen roll on the table as napkins. ‘Yassin was taken away.’ Kell gathered his thoughts as he drank a mouthful of wine. ‘The truth is – yes – I didn’t really care what happened to him. I didn’t think about what methods the Egyptians would use, what might go on in Cairo or Guantanamo. As far as I was concerned, here was a young British man whose sole purpose in life was to murder innocent civilians – in Washington, in Rome, in Chalke Bissett. I thought he was a coward and a fool, and the truth is I was glad to see him in custody. That was my sin. I forgot to care for a man who wanted to destroy everything that it was my job to protect.’

Elsa poured olive oil on to the pasta and stirred the courgettes and garlic into the long broad strands of tagliatelle. Kell could not interpret her mood nor sense where her opinion lay.

‘So you’re the fall guy?’ she asked and he knew that he must be careful not to moan or complain. The last thing he wanted was for this lovely girl to feel pity for him.

‘Somebody had to be,’ he said, and remembered how Truscott had cut him loose: authorizing an SIS presence at the Yassin interrogation from a desk in London thousands of miles away; then brazenly accusing Kell of acting beyond the law when, years later, it looked as though the Foreign Secretary was going to get cooked by the Guardian over rendition. Kell had been thrown on the mercy of the courts, given a suitably anonymous, Orwellian codename – ‘Witness X’ – and pitched out of the Service.

‘I’ll tell you this,’ he said, ‘and then I’ll stop talking. We are in a political and intelligence relationship with the Americans that goes deeper than anybody realizes and deeper than anyone is prepared to admit. If British spies see their American allies engaged in methods with which they disagree, what are they meant to do? Ring up Mummy and say they disapprove? Tell their line managers that they want to come home because they don’t feel comfortable about things? This is a war we are fighting. The Americans are our friends, whatever you thought of Bush and his chums, whatever your feelings on Guantanamo or Abu Ghraib.’

‘I understand that …’

‘And too many people on the Left were interested solely in demonstrating their own good taste, their own unimpeachable moral conduct, at the expense of the very people who were striving to keep them safe in their beds.’

‘Have some food,’ Elsa said. She rested her hand on Kell’s neck as she set the bowl in front of him, the softness of her touch a gesture of a friend’s understanding as much as it was an indication of her desire for him.

‘The kindest thing you can say about Yassin is that he was young.’ Kell suddenly didn’t feel like eating. He would have pushed the bowl to one side if it had not seemed rude or petulant to do so. ‘The kindest thing you can say is that he didn’t know any better. But try telling that to the fiancée of the doctor he would have blown up on the Tube, the grandson of the old man obliterated on the top deck of a bombed-out bus in Glasgow. Try telling that to the mother of the six-month-old baby boy who would have died of his injuries if Yassin had blown himself up in a Midlands shopping centre. Looking back at the evidence, they might have pointed out that a man like Yassin Gharani, with that back story, wasn’t likely to be in Pakistan retracing the steps of Robert Byron. He was getting high on hate. And because of what happened to him, because we allowed ourselves to hate him in return, Yassin was given a cheque by Her Majesty’s government for eight hundred and seventy-five thousand pounds.’ Elsa sat down. ‘Almost a million quid, in our age of austerity. Compensation for “ill treatment”. Now that’s a lot of taxpayer money for an individual who would, in all likelihood, happily have blown up the very High Court that found in his favour.’