‘Yes, a young lady there who’s occasionally helpful to us.’

‘Muslim?’

‘Of course.’

‘Name?’

‘Really, Patrick, the questions you ask. More tea?’ With a hint of ceremony, J topped up their cups, helped himself to a splash of milk and dropped in two lumps of sugar which he stirred in with great deliberation as if the circling stew of pale brown might contain unsuspected secrets of its own. ‘We’re logging the phone numbers Kareem’s calling – cheap surveillance tool and surprisingly productive – it shows a call that morning to a red velvet-lined restaurant in W2 – London’s little Arabia. We send along a girl and boy team, camera in his tie-pin, microphone and recorder in her handbag.’ J took the second, thicker file from below the first and extracted a document and a single photograph. ‘Pay dirt.’

Patrick examined the photograph; one face was just recognisable from the saturation press coverage of the 7/7 bombings, the profile of a second from the photographs J had already shown him. The backs of two female heads were in silhouette, impossible to identify. The document was a verbatim transcript of a multi-party conversation. ‘Wow,’ he said. ‘Mohammad Sidique Khan dining with Kareem bin-Jilani.’

‘Yes,’ said J, ‘wow, as you put it. The oddity is that this was taken because we were monitoring Kareem. Not Sidique Khan. His name had come up but he was never considered a serious threat. That was the tragedy.’ He pointed to the transcript. ‘When you plough through this, you can see that Kareem was unfamiliar with Sidique Khan. It was this other chap – turned out he’s called Aaqil – who’d brought him along.’

‘What about the others?’

‘The girl with the hijab was – is – called Maryam Saeed Britaniyah, once upon a time the rather less exotic Marion Green. Middle-class family, wellish-heeled, she was working as a PA at a city hedge fund. Where, by coincidence, the bin-Jilani family had investments which Kareem, as the London presence, kept an eye on. She apparently fell in his thrall.’

‘The other girl?’

‘We put a tracker on her but she ended up clear. Not part of the picture now. He tended to whisper to her so we didn’t get much.’

‘A tracker?’

‘Yes, soft tail, not a combined op. Just two of ours. Girls, of course. Show respect and all that.’

‘For how long?’

‘Couple of months. I seem to recall she spent rather an uneventful summer.’

‘You’re saying I was under surveillance for two months,’ said Sara dully. Up till now, she’d been listening in silence. ‘Just because once at a restaurant I sat next to a man they suspected.’

The grey sky was blackening, promising rain. ‘Let’s move,’ said Patrick, ‘we’ll go back and cross the road. There’s a Pret we can take cover in.’