He screwed his eyes at her, his disappointment obvious. Or was it dissatisfaction? Either way, she had to download him first; only then would she know what she needed to give back.

He sighed, turning from her to the river. ‘OK. J gave me some background. How, since 9/11, whatever happened elsewhere in the world, they’d been successful at home. Plots were intercepted, plotters imprisoned. But then came 7/7…’

‘You spoke of shock and the luck of life and death,’ said J. ‘My reaction to the 7th of July was anger. A fury that we didn’t stop it. That we didn’t know enough. Or, rather, that we had much of the knowledge but we didn’t know how to prioritise it. Or make the right connections. We were an army bristling with rockets and guns but without a spotter behind enemy lines. We at MI5, MI6, Special Branch, NCIS – that’s the National Criminal Intelligence Service, Patrick—’

‘Yes, J, I know what NCIS is—’

‘We all vowed better co-ordination. “Dare to share” became the new motto. Kareem was one of its first opportunities.’

J handed the photographs to Patrick. ‘Look at him. Get to know him. Try to understand what’s inside.’

‘Don’t I get to meet him?’

‘Oh yes. You’ll meet him all right.’ J took a breath while Patrick obediently stared at the photographs. ‘In fact it began well before 7/7. Back in late 2003. During the Christmas holidays, some Pakistani post-grads from Queen Victoria College, London, boarded an Air South Asia Express flight to Islamabad. One was called Kareem Abdullah bin-Jilani, twenty-six years old and writing a thesis on the mathematics of aerodynamics. Rather than turning right into the plane and heading for economy like the other five, he turned left into first. A stewardess noted how the group had separated and thought it unusual enough to inform the captain.’

He paused; Patrick, looking up from the photographs, was paying full attention. ‘You’ve got to remember – it was less than two years since 9/11. And there had been the attempt by the “shoe bomber” to blow up an American plane in midair. The captain took an informal stroll through the first-class and economy cabins, eyeing them up. He saw nothing amiss but took two precautions. He ordered a manual check of the group’s hold baggage and rearranged the seating plan to allow his two plain-clothes armed marshals to be in close sight of them.

‘But the single PhD student sitting in first class kept niggling at him. He radio’d ahead to the airport to suggest that passport and customs might like to take a look. This request itself was so out of the ordinary that the airport authorities passed it on to ISI.’

‘ISI?’

‘The Pakistani intelligence service. You don’t know everything, do you?’ he said sharply. ‘They in turn asked the local MI6 head of station if Kareem’s name was on their files. He wasn’t. From then on, he was.’