‘He was clearly a diplomat attached to the Russian Embassy. You had no reason to guess that he was a member of their intelligence apparatus?’

‘I had my suspicions, but I wouldn’t put it any higher than that.’

‘And they were confirmed when he gave you this extraordinary piece of information – that Igor Borodin regularly hosted get-togethers for some of Russia’s most senior intelligence officials on his super-yacht in the summer.’

‘Yes.’

‘Were you surprised that Sergei offered you this information?’

The more Kate was asked, or considered, this question, the less she liked it. The way she had taken it at face value so quickly did not reflect well on her. ‘He later explained the context. He’d been posted to Istanbul prior to coming to London. The consulate there had been forced to intervene after a young girl who had been on the yacht claimed to have been raped by a Russian man.’

‘But were you not a little startled that this … friend you had not seen for years and years suddenly offered you such an extraordinary tip-off?’

There was no way around it: she should have been. And they all knew it. ‘Look, we’ve been over this time and again. I hadn’t set eyes on Sergei since I left Russia. It was nice to see him again and his sincerity didn’t seem to be in doubt. I concluded, in consultation with my superiors, including Ian Granger …’ she glanced at Suzy, who still gleamed with impending triumph ‘… that it was worth a shot. If our operation succeeded and we managed to get a bug on to the yacht, we would treat the intelligence we picked up on its own merits.’

‘And what a bombshell it was,’ Williams said.

‘Yes, but easily verifiable. We concluded that if the prime minister did turn out to have prostate cancer, then the Russians clearly had a highly placed source.’

‘Very convenient,’ Suzy Spencer said, from the sidelines. Everyone else ignored her.

‘So you really had no contact from Sergei Malinsky in the period between your departure from Russia as a student and your reunion in London?’ Young asked again.

‘No.’

‘None at all?’ Williams asked, sceptical. ‘No friendly message, letter or postcard?’

‘None.’

Young nodded, as if her section of this interview was concluded. Williams took the file back from her and turned a few more pages. Kate had the sense they were enjoying this, but not as much as Suzy Spencer. ‘After your probation period,’ Williams said, looking at the file, as if its contents were news to her, ‘your first posting was to work undercover at the consulate in Hong Kong.’

‘If that is what it says.’

Williams smiled again, like a cat playing with a mouse. ‘Stuart accompanied you?’

‘Yes.’

‘He was also able to secure a job in the consulate?’

‘In the trade delegation, yes.’

Williams nodded. ‘Since then you’ve been based in London?’

‘Yes. The trajectory of Stuart’s career made permanent location abroad difficult.’