‘Have they ever worked out how Daniel got out of the country?’

‘Not really. Last I heard from MI5 they thought it might have been via Ireland. They think he left London the day you and Anya saw him. Must have had places to hide on the way.’

‘They don’t still think he was really doing it, knowingly supplying terrorists, do they?’

‘MI5 don’t, as I said before. The police are more reluctant to declare him innocent.’

‘I told Deborah you’d said MI5 think he was an innocent victim manipulated by the people in that mosque. So far as he was concerned he was doing real charity work. That might be some comfort to her, if anything can be.’ She paused. ‘But he might have realised when he got there, don’t you think? They can’t have seemed like ordinary charity people.’

Nor did they, according to Herm, who had found plausible reason to distance himself after secretly substituting Tresco/1’s phone. He had seen Daniel but not spoken to him, describing him as quiet and subdued, probably intimidated, speaking no Arabic. Herm had the impression that Daniel knew something was wrong – perhaps knew by then that everything was wrong – but had no idea how to get out of it. He was virtually a prisoner. Herm had heard Tresco/1 and the other two discussing what to do with him, whether he was worth a ransom to anyone, or whether they could put him to work, or to death. Tresco/1 just said, ‘Come with us, brother,’ in English, when they were getting in the car. They were the only words anyone said to him in Herm’s presence. The drone must have already logged on to the phone’s signal and the controller was presumably waiting until the car was well away from any buildings or other vehicles in order to minimise collateral damage.

Later, as they drove along the Embankment, Sarah said, ‘I’m never sure about the morality of these drone things. I know you say it’s ethically no different from a fighter pilot spotting an enemy vehicle and bombing it but it’s so cold-blooded, just a controller sitting in a booth thousands of miles away, safe and sound, not risking himself at all. It’s waging war without fighting. Doesn’t seem fair.’

‘They kill fewer innocents than bombs or bullets or shells, more precise, more accurate. But I agree, I wouldn’t like to have to do it.’

‘You – you, the Office, I mean – don’t get involved in this sort of operation, do you? The sort that killed Daniel.’

Charles paused as he turned into Smith Square, pulling round a taxi that was disgorging evening concertgoers. He had never lied to Sarah. He didn’t now, not literally, except by omission. He wasn’t sure whether that counted. ‘Drones are MOD operations. They actually do them. Them or the Americans.’