“Prime Minister.” Infuriatingly, Kydd did not wait to be spoken to, but launched straight in. “This is Dave McKinlay, the Deputy Supreme Allied Commander Europe. He’s just flown in from NATO’s strategic headquarters in Belgium for this briefing.” Walker noted a bulky, strong-looking, gray-haired general who, in his Royal Marines uniform and badges of rank, looked like another conventional soldier. However, a second glance revealed a steely look and the broken nose of a former rugby player and he realized that, although very different, the two generals were probably very much out of the same lethal mold.

“It’s good to meet you, General,” said Little, shaking his hand. “Where does NATO stand on this?”

“I’m here, Prime Minister, because nobody else, and that includes the Americans, can do what GCHQ have got planned and we fully support that plan. My role is to ensure the closest possible cooperation between what GCHQ can do and the NATO strategy. So, I’m here to listen in and take the plan back to SACEUR.”

“We really appreciate you finding time to visit us, Prime Minister,” said Berry, taking back control. “We’ve got a plan which I think you’ll find of interest. I’ve brought together the team who’ve been working this particular issue, so I’m going to leave it to them to tell you what they’ve achieved.”

“I hear you’ve found a way into Russia’s nuclear command and control system,” said Little, imposing his authority in turn. “If that’s so, it’s a potential war winner. But please continue.”

“Certainly, Prime Minister,” answered Berry. “But without going into technical detail. Not because we think you won’t understand it. More important, it’s not something you need to know, so it’s better left unsaid.”

“Look here, Ian,” said Little, “I only managed to scrape a Physics with Chemistry ‘O’ Level. There’s no chance of me letting any technical cats out of the bag!”

“Be that as it may, Prime Minister, but what I’m saying is, you may not want to know . . .” As he said this, Berry was looking hard at Walker, his meaning clear: he was not revealing any secrets to the Prime Minister’s PR man, regardless of his top level of clearance.

The Prime Minister also looked at him, but instead of leaping to his defense as his predecessor would have done, he waved a hand as if to push the issue aside. “Point taken. Continue.”

“Thank you, Prime Minister. In essence what we’ve done is think through the problem as if we were terrorists hacking a nuclear command and control network. I’m going to leave it to Nicola Allenby, the team leader, to talk you through it. She’s just back from PJHQ, where they are setting up this attack . . . If you authorize us to instigate it, that is.”