‘I’ll keep you posted. Meanwhile, there’s something I wanted to run by you,’ said Shepherd. He took the RAF thumb drive from his pocket and held it out. ‘I’ve got pictures of three guys on the roof, just before the missile hit. You’ll be able to confirm that our two targets are there, but the sniper might have got away.’

Willoughby-Brown took it. ‘Can’t win ’em all.’

‘Be handy if you could ID the sniper. Get the technical boys on it.’

‘Syria’s full of snipers,’ said Willoughby-Brown. ‘It’s not really our problem. We’re more interested in the British jihadists and, so far as I’m aware, there are no Brit snipers out there.’

Shepherd gestured at the thumb drive. ‘That guy’s special,’ he said. ‘He was looking at a shot of a mile or so. And there were two men on the roof with him. Two spotters is unusual. And I think he had even more jihadists watching out for him. That was how he managed to avoid the explosion. It looks to me like IS were going out of their way to protect him, which would make him a high-value target.’

‘But not for us.’

‘The Americans, then. I’m serious, Jeremy. There’s no way of knowing how many guys that sniper has killed. At least get your people to do facial recognition on the pictures, see if he’s known.’

‘Okay,’ said Willoughby-Brown, but Shepherd had heard the lack of conviction in his voice.

‘What now?’ he asked. ‘I’m getting a bit tired of sitting in that container watching video feeds.’

Willoughby-Brown grinned. ‘I can remedy that,’ he said. ‘I need you out in Turkey.’

‘Since when has Five operated in Turkey?’

‘We’re liaising with Six.’

‘They don’t have their own people?’

Willoughby-Brown grimaced. ‘Why are you giving me a hard time, Daniel? I thought you might jump at a bit of overseas travel. Get you out of your rut.’

‘What rut?’

‘I just meant a change is as good as a rest. Revitalise the old batteries while serving Queen and country. But the threat is a UK one. We have a source in a refugee camp, a chap by the name of Yusuf Yilmaz. He’s made contact and is offering us names and photographs of Islamic State fighters who have passed through the camp pretending to be Syrian refugees. He helped them get the paperwork. He says they’re on their way to Europe. The UK in particular.’

‘So fly him over and debrief him in Thames House.’

‘I wish it was that easy,’ said Willoughby-Brown. ‘He has a number of demands, including fast-track to British citizenship and rather a lot of money.’

‘If the intel’s good, what’s the problem?’

‘Because we don’t have the intel. All we’ve got is an initial contact, via an agent of ours who works for an NGO out there. We need someone to go and talk to him, to see if he’s offering us gold or shit.’