‘No comment. I’ve told you I’m not going to get into the areas our inquiry is considering.’

Williams passed the file to her blonde colleague, who turned the pages with long, slender fingers, then pulled out a sheaf that was stapled together. ‘We’d like to ask you some questions about your former contact, Sergei Malinsky.’ Suzy Spencer looked up from the floor and gave Kate another smile of triumph, in light of which Kate mentally braced herself for what was coming. ‘Were you aware of his position within the Russian intelligence hierarchy?’

‘Not precisely, as I have said many times.’

‘But if you had to guess?’

‘I don’t guess.’

‘Please answer the question, Mrs Henderson.’

‘In our last conversation, he did not deny that he was a member of the GRU.’

‘Yes,’ Young said. ‘A very senior one.’ She pushed across a still photograph of Sergei sitting with the head of the Russian military intelligence agency and the Russian president at the Sochi Winter Olympics in 2014. ‘I believe some of our colleagues showed you the video this still photograph has been taken from during the investigation they conducted into the death of your former deputy, Ravindra.’

‘We’re going over old ground here. I knew Sergei was a senior member of the Russian intelligence hierarchy. I didn’t know precisely which agency he worked for at the start, but I trusted him. That was why we took seriously his tip-off about the meeting on Igor’s super-yacht and decided to attempt to bug it accordingly.’

‘But you later managed to clarify that he was a senior operative of the GRU?’

‘He never confirmed as much, but that was my understanding, yes.’

Emma Young tilted her head to one side, as if a thought had just occurred to her. She had a studious quality, and Kate sensed she was new to this kind of interrogation, but still confident of the hand she had to play. ‘Would you mind just talking us through once more your relationship with Sergei and how this tip-off came about? I’m sure you would agree it is really central to our assessment of this entire affair.’

Kate was about to refuse, but something about their poise was unsettling her. She wanted to force them to reveal their hand now. ‘We met while I was studying Russian in St Petersburg. We became friends, not lovers as is sometimes alleged.’

‘But you lost touch after you left?’

Kate could see what Young was driving at. She sighed. ‘Yes, it’s true, he wanted more than friendship and I was then firmly hitched to the man who became my husband, Stuart. I could not, or would not, reciprocate Sergei’s feelings. But we didn’t part on bad terms. We remained extremely fond of each other. We understood that our parting at the end of that summer was a permanent one and we would not remain in touch.’

‘And you didn’t see him again until he approached you at a social function in London?’

‘That’s right.’