One of the Hellfires had taken out the building, specifically an AGM-114P Hellfire II, specially designed to be fired from a high-altitude drone. The Hellfire air-to-surface missile was developed for tank-hunting and the nickname came from its initial designation of Helicopter Launched, Fire and Forget Missile. But the armed forces of the West soon realised that, when fired from a high-flying drone, the Hellfire could be a potent assassination tool for taking out high-value targets. It was the Israelis who had first used it against an individual when their air force killed Hamas leader Ahmed Yassin in 2004. But the Americans and British had taken the technique to a whole new level, using it to great effect in Pakistan, Somalia, Iraq and Syria. Among the terrorists killed by Hellfire missiles launched from drones were Al-Shabaab leader Ahmed Abdi Godane, and British-born Islamic State terrorist Mohammed Emwazi, also known as Jihadi John.

The Hellfire missile was efficient and, at less than a hundred thousand dollars a shot, cost-effective. It was just over five feet long, had a range of eight thousand metres and carried a nine-kilogram shaped charge that was more than capable of taking out a tank. It was, however, less effective against a stone building. While there was no doubt that the men on the roof would have died instantly, the sniper might well have survived, if he had made it outside.

Shepherd twisted in his seat. Alex Shaw, the mission coordinator, was sitting at his desk in front of six flat-screen monitors. He was in his early thirties with a receding hairline and wire-framed spectacles. ‘What do you think, Alex? Did we get him?’

‘I’d love to say yes, Spider, but there’s no doubt he was moving.’ He shrugged. ‘He could have got downstairs and out before the missile hit but he’d have to have been moving fast.’

Shepherd wrinkled his nose. The primary target had been a British jihadist, Ruhul Khan and it had been Khan they had spent four hours following until he had reached the roof. It was only when the sniper had unpacked his rifle that Shepherd realised what the men were up to. While the death of the British jihadist meant the operation had been a success, it was frustrating not to know if they’d succeeded in taking out the sniper.

Shaw stood up and stretched, then walked over to stand by Shepherd. Donoghue had switched the camera back to regular HD. There were several pick-up trucks racing away from the ruins of the building, and a dozen or so men running towards it. None of the men on the ground looked like the sniper. It was possible he’d made it to a truck, but unlikely. And if he had made it, there was no way of identifying him from the air.