Al-Hussain thanked him and climbed in. The door slammed behind him. As he watched through the window the three men outside embraced again, then the IS fighter headed back to the border. Two minutes later the SUV was bouncing along the rough ground. The driver and the second man had both donned night-vision goggles and kept the headlights off. There was a cloth package on the seat next to him, which al-Hussain unwrapped. Inside he found a small loaf of hard bread, some olives and soft goat’s cheese. Another, smaller, package contained a bundle of khat. Al-Hussain put aside the food and started to chew the leaves.

Omar Hassan lived in Salford, just five miles south of the park where he was to meet his contact. It would have taken just twelve minutes by taxi but he travelled by bus, tram and then on foot. The journey took him almost an hour but gave him plenty of opportunity to check that he wasn’t being followed.

The instructions detailing where he was to go and whom he was to meet had been placed in a mail folder in a Yahoo account. It was the way he had communicated with his Islamic State handlers for more than five years, ever since he had returned from a training camp on the Pakistan border. Hassan had flown to Islamabad in 2010 with four of his friends from Greater Manchester, ostensibly to attend a wedding, then to spend time getting to know the culture of the country their parents had come from. All five were British-born, the sons of parents who had emigrated to the UK during the fifties and sixties.

They had been teenagers when they had made the long trip to Pakistan, and Hassan’s parents had expressed their reservations. Hassan was the youngest of five, four boys and a girl, and was the only one who had ever expressed any interest in connecting with his Pakistani heritage. The local imam had come to see his parents to ask their permission for him to go. What they didn’t know was that the imam was a recruiter for al-Qaeda, selecting men suitable for jihadist training. He was a kindly man, well known in the area for his charitable works, and he had sat in the Hassan house for more than an hour drinking hot mint tea as he explained how beneficial the trip would be for Omar’s Islamic studies, that a Saudi Arabian charity would bear the costs and pay him a handsome stipend.

Eventually Hassan’s parents agreed, and he flew to Pakistan a month later. He attended the wedding and returned with lots of photographs of the ceremony and the celebrations afterwards. There were also photographs of him visiting sights of cultural interest, and attending various mosques. But there were no photographs of the place where he and his companions had spent most of the trip: an al-Qaeda training camp across the border in the rugged mountains of Afghanistan. There, Hassan had been trained to fire a range of weapons, from handguns to shoulder-mounted ground-to-air missiles, and instructed on how to deal with explosives, from making small IEDs to constructing landmines large enough to destroy a tank. His instructors had groomed him in tradecraft as well, explaining how to arrange a clandestine meeting, how to detect a tail, and how to remain undercover and invisible for years.