Kate stared at the board for a moment and then wrote ‘David Snell’. ‘Fast forward to last year and, while we were investigating the prime minister’s alleged Russian links, Rav and I started to look into this guy, who had helped the PM facilitate some rather nebulous “consultancy” work in Africa after his stint in the army.’

‘I’m not sure I’m following,’ Callum said.

‘Forget the detail. It doesn’t matter right now. We were trying to work out the source of the prime minister’s unexplained wealth. The key thing is that Snell told us SIS had looked into all this years ago. Rav and I were pretty dumbfounded. When I got back to the office, I discovered that the investigation had been shut down by the chief, Sir Alan Brabazon.’

Kate let that sink in. ‘The obvious question was why,’ she said.

‘And the less obvious answer?’

‘I discovered that, far from turning down Irina the KGB translator, Ian had reeled her in and touted her around the bazaars as a revelatory find. She seemed to have access to an ever-increasing supply of grade-A intelligence, including details of a KGB sting on the German finance minister, who had some pretty sordid habits.’ Kate sighed. ‘To cut a very long story short, Sir Alan gave this information to James Ryan, by then foreign secretary, who used it as some crude negotiating tactic with the Germans. They angrily exposed it as fake. Ryan looked a fool and was livid. Shutting down the investigation into his Africa links was the price – implicit or explicit, I’m not sure which – for keeping Sir Alan and Ian in their jobs.’

‘How did you find that out?’ Callum asked.

‘I’d prefer not to say.’

‘You have your sources?’

‘I’ve worked for the organization a long time.’

‘How does that have any bearing on what’s happened in the past year?’ Callum wondered.

‘The truth is, I don’t know. I just have a hunch that this was where it began. It’s the same kind of play. It has Borodin’s fingerprints all over it. They used Irina to lure us in, set us up and then deliver the sucker punch. It worked so well, I think they ended up wanting more of the same. Only this time, they went for a much bigger, bolder plan.’ Kate tapped her pen against the board. ‘I think it started here, with Operation Cyclone.’

‘So what you’re really saying,’ Grove said, ‘is that Agent Dante has been in place for twenty years or more.’

‘Yes.’

‘How can you be sure that these events are connected?’ Callum asked.

‘I can’t. But in intelligence work, you have to rely on your instincts. If things seem to fit a pattern, then there’s a high chance they’re connected, even if you can’t immediately see how.’

‘And Dante, whoever he or she is, is in a senior enough position to be able to orchestrate these operations within SIS?’

‘Yes. Or at least to take a view on how they might pan out and help them with intelligence on the personnel involved.’