‘The underage girls in Kosovo?’ Callum asked.

‘Yes. In the course of overseeing that defection in Georgia, I discovered that my children had been kidnapped back here, apparently by gangsters Moscow had hired. I had to abandon Borodin and return to London. The defection did not go ahead.’

‘Your children were all right?’

‘I suppose it depends on your definition of all right, but they’re alive, which is more than I can say for the poor nanny we used in Istanbul and my deputy, Rav, who were casualties along the way.’

‘So this new evidence suggests that the original conversation on the super-yacht was a set-up to fool us and Borodin never intended to defect, merely to plant more damaging material in the British system in the form of this video?’

‘Yes.’ Kate reached for a felt tip and headed for the whiteboard at the end of the room. ‘Which brings us to the latest twist. An apparent Russian intelligence agent has approached one of our diplomats in Istanbul to claim that this entire business was indeed a giant misinformation ploy conceived years ago to create disorder, confusion and bitterness within the British political system, just as we have seen in America in recent years.’

‘You think what we saw in the US was all misinformation?’

‘That’s a long story for a different discussion. Some was, some wasn’t. But they win either way, because we lose sight of what the truth is. And along the way, we turn against ourselves, and the consensus upon which all democracies ultimately depend is lost.’ Kate scrawled ‘Agent Dante’ at the top of the board. ‘This mysterious Russian source in Istanbul claimed there is a traitor at the very top of SIS in London, who has helped Moscow orchestrate this operation from the start. Agent Dante. That is why we’re supposed to be conducting this inquiry entirely outside the remit of our existing intelligence services – both SIS and the Security Service.’ Kate looked at him. ‘The question is, if the prime minister is innocent, how do we prove it? Our best chance is to find out who Agent Dante is and expose how he, or she, has been able to cause so much havoc.’ On the left-hand side of the board, Kate wrote ‘Cyclone’. ‘So, how do we begin the search for someone who has remained successfully hidden for many years? I think here, winding back in time to Operation Cyclone.’

‘Go on,’ Grove said.

‘Shortly after I joined the Service, I was working on an op tracking an early Al Qaeda affiliate in Istanbul – where all roads seem to lead right now – when I was approached through our station chief, Yusuf, by a young Russian KGB translator called Irina, who wanted a new life in the West. It was 1997 and the former Soviet Union was still in turmoil, so it was fairly easy to pick up KGB agents, but I dutifully passed on the approach to Ian Granger, head of the Russia Desk at the time, and thought no more about it. I assumed we’d turned her down.’