“So,” said Lockhart, “you asked me who I’d suspect. Well, I don’t think I suspect anyone.”

“Shall I tell you who I’d suspect, if it was me?”

Lockhart opened his hands out to Worstead. This was ridiculous, but almost fun, an intellectual challenge.

“I’m all ears, Andrew.”

“I’d say it was Pugh.”

“Pugh?”

“That’s right.”

“For Pete’s sake, why Pugh?”

“Because I don’t trust him.”

“That’s hardly evidence.”

“Wait. He seems to have a special relationship with Strasser, almost as if he can tell Strasser what to do. You know what he was doing before he joined the unit, don’t you?”

“Broadcasting, wasn’t it?”

“That’s right. For the Concordia Bureau in Berlin, broadcasting all sorts of nonsense over the air to be received back home. He’s been doing it for years apparently, and even seems proud of it.”

“This is a long way from faking letters from my wife.”

“Hold on. As a result of being in Berlin for so long, I get the impression Pugh has made some very powerful friends, including Hillen-Ziegfeld of course, and Vivian Stranders, who you told me Strasser had told you about. And men like them have contacts back in Britain, spies of course, who are quite capable of unearthing information about people’s pasts. Do you follow me?”

“Of course I do, but it’s preposterous. You think the Germans have people foraging around Britain for details of my private life? It’s absurd!”

“Perhaps it is. But then ten years ago we would have found it absurd to be sitting in a restaurant in the middle of Germany dressed up as SS soldiers.”

“Fair point, but in my experience the Germans have a bad record with their spies.”

“Oh yes?”

Lockhart paused. This was going back to his work in Whitehall, in Military Intelligence.

“You’ll have to forgive me, Andrew, I can’t tell you much more.”

Worstead’s eyes narrowed.

“Secrets?”

“Yes, Andrew—secrets. Even from you, I’m afraid.”

“No, that’s quite all right. I wouldn’t want to be burdened with them!”

Lockhart had expected another display of chippiness, and it came as a relief that it hadn’t materialized.

“Now then,” he said, “let’s look at this menu properly. What have we got? Crikey! ‘Pork in a cream and apple sauce’—I can see why Strasser always comes here!”

“Quite! This menu is music to my ears.”

The sensation was almost physical. Somewhere in his head, Lockhart could feel two facts, two hitherto useless pieces of information, connecting and reacting, spurred on by the word “music” as a catalyst. Strasser had told him that Stranders’s father was a music professor. The organist at Lockhart’s wedding had been a music professor called Saunders. But Lockhart hadn’t been sure it was Saunders, because the organist, well into his eighties, had only mumbled his name.

“John? Are you all right? You look as though you’ve seen a ghost.”