“Tell me the route you took to Moscow.”

“I drove from my home in Cornwall to Heathrow. I took a plane to Manchester, a coach to Newcastle—”

“And from there you flew to Amsterdam, where you took a barge along the Rhine, the Main and the Danube to Vienna.” Pengelly shifted uneasily in his seat. “You then traveled from Vienna to Warsaw by train, before finally boarding a plane to Moscow. Shadowed every inch of the way by a succession of British agents, the last of whom accompanied you on your flight to Moscow. He didn’t even bother to get off the plane before going back to London because he knew exactly where you were going.”

“But how is that possible?”

“Because Brandt informed her English handler that I had ordered you back to Moscow even before she told you about it. Comrade, they literally saw you coming.”

“Then my whole operation is blown apart and there’s no point in my returning to England.”

“Unless we turn the situation to our advantage.”

“How do you plan to do that?”

“You will return to England by an equally circuitous route, so they think we have no idea that Brandt has betrayed us. You will then go back to work as usual but, in future, every message we send through Kramer to Brandt, the British will be confident they have intercepted.”

“It will be interesting to see how long we can get away with that before MI6 begin to wonder which side she’s on,” said Pengelly.

“The moment they do, it will be time to dispose of her, and then you can return to Moscow.”

“How did you find out she’s switched sides?”

“A piece of luck, comrade commander, that we nearly overlooked. There’s a member of the House of Lords called Viscount Slaithwaite. A hereditary peer who would be of no particular interest to us, except that he was a contemporary of Burgess, Maclean and Philby at Cambridge. Once he joined the university’s Communist Party, we no longer considered recruiting him as an agent, although he’d like you to believe he’s the sixth man. Over the years Slaithwaite has regularly passed on information to our embassy which, at best, was out of date and, at worst, planted to mislead us. But then, without having any idea of its significance, he finally came up with gold dust. He sent a note to say that Lord Barrington’s wife—he has no idea that she is one of our agents—was seen regularly in the House of Lords tearoom in the company of Baroness Forbes-Watson.”

“Cynthia Forbes-Watson?”

“No less.”

“But I thought MI6 pensioned her off years ago?”

“So did we. But it seems she’s been resuscitated to act as Brandt’s handler. And what better cover than tea in the House of Lords, while Lord Barrington toils away on the front bench.”

“Baroness Forbes-Watson must be eighty—”

“Eighty-four.”