Meg Simpson stormed in like a thundercloud. She didn’t bother to wish any of them good morning. And more pressingly, from Kate’s point of view, she did not show any inclination to reach for the pastries or even the coffee. Kate weighed the social acceptability of opening the score.

C hadn’t bothered to join them at the table. ‘Would you care to join us, Sir Alan?’ Simpson asked, with more edge than the situation appeared to demand. Kate wondered if she knew of his wife’s illness. He did as he was asked, looked at Kate and, as if reading her mind, reached for the coffee and a pastry. She mouthed her thanks and he allowed himself a smile.

‘Sir Alan has briefed me,’ Simpson said.

‘It was an excellent operation, conducted with the utmost professionalism,’ Ian offered, ‘but I hold to my initial view that—’

‘I am well aware of your views,’ Simpson shot back. Ian’s face reddened. It occurred to Kate that if Ian was Viper, or some other agent working for the SVR or the GRU or any other arm of the Russian state, he was not subtle in covering his tracks. Simpson shuffled uncomfortably in her seat. She stared at the coffee pot in front of her. ‘I do not find myself willing as yet to write the letter you say you need, or to set in train the actions it would instigate, or deal with the consequences that might arise.’

They waited for her to elaborate.

‘You may be inclined to view that as political cowardice. I would prefer to see it as caution.’

‘The difference is academic,’ Sir Alan said. ‘We are not interested in motive, only conclusion.’

Now it was her turn to look stung. ‘I am aware that this is not what you wanted to hear.’

‘We have a bounden duty here that is not, I think, in question.’

‘I disagree. Our greatest duty is to preserve the integrity of our democracy, which, I am afraid, includes an essential belief in it.’

‘It’s hard to think of anything that would erode it more swiftly than the idea that we all sat here knowing the prime minister was working for our mortal enemy, not to mention his past actions, and resolved to do nothing about it.’

‘But that is where all this falls down for me. Upon reflection, and taking into account what you’ve told me, I don’t think I do yet believe that.’

‘Kate has watched the video, in full, revolting detail, an act of conscientious duty in itself. She is not in any doubt that it is genuine.’