Ernst gasped. Even Julia looked shocked.

Josef stared at her, then laughed out loud. 'My word, Ernst, this half-breed of yours has a bit of spirit!'

'Yes, she does,' Ernst said testily.

'So, Ernst, your training is going well? All that seasickness and lumping it up the beaches?'

'The preparations are proceeding,' Ernst said neutrally.

'Yes, they are, in fact, at levels more elevated from you than the eagle flies,' Josef said. 'The Fuhrer has issued a final directive, I am told. The invasion of England even has a name now. Operation Sea Lion! But the details are still being argued over among the military command. I need something to draw on.' He patted his pockets. 'Damn.' He lifted the cups and glasses from the table, and pulled away the lace tablecloth to expose a surface of old wood, dark and so polished it had the look of satin. He took out a pocket knife and with brisk strokes scraped a map into the table's surface. 'This will have to do.

'Look here. This bit of coastline is the most suitable to mount an invasion, for it is here that Europe comes closest to England. One can simply hop across the Channel and assail the coasts of Sussex and Kent, and be only a few hours' drive from London. The Navy want to plan on the basis of a narrow front, for that is more defensible from the sea than a long stretch of the Channel; the Army, though, don't want to be bottled up on land, and argue for a wider front…'

He continued to sketch with his knife, drawing attack lines and defensive perimeters, cutting and splintering the tabletop. Ernst watched the faces of the women; neither of them reacted to this bit of petty vandalism.

Claudine asked, 'You are a mere standartenfuhrer. Why would you know all this? Perhaps you are simply trying to impress a woman you have called a whore.'

'You do have spirit, don't you? I am here advising the Waffen SS. The military arm of the SS, which strictly speaking is a Party organisation. But I work with the Ahnenerbe.'

'Which,' said Julia, 'is Himmler's research and cultural institute.'

'I have worked with Himmler himself. So you see, my dear, your lover's brother has contacts in high places. Aren't you impressed?'

Claudine said, 'It is already a month since the surrender of France. By waiting so long you have given the English time to prepare.'

Josef nodded, impressed again. 'Actually some have said exactly that. General Milch, Goering's second-in-command, for example. It is a basic principle that one should pursue a defeated enemy. Milch argued we should have mounted an airborne invasion as soon as we reached the ocean, in June.'

Julia said, 'I think the Fuhrer continues to hope that my countrymen will come to their senses. After all England's land army is severely depleted after the bulk of it was lost at Dunkirk.'

'It's true Hitler has made peace offerings,' Josef said. 'With sensible terms: a free hand in Europe in return for the security of the British Empire. All ignored or rebuffed. How unreasonable! Especially when you see how well we treat the conquered French.' He grabbed the top of Claudine's thigh and squeezed it.

'You're a pig, Josef,' Ernst murmured. The talk of war seemed unrealistic, a fantasy in the bright summer sunlight, amid the gentle sound of voices, the clink of cutlery and glasses. 'Do you think we will invade, Josef, when it comes to it?'

'Well, what do you think? The invasion fleet is in the harbour just over there. That doesn't come cheap, you know; every barge that's brought here can't be lugging machine parts or coal up and down the Rhine.'

'True. But we need a show of strength to keep the British on the ropes, don't we? If the barges ever sailed, the Royal Navy would overwhelm the Kriegsmarine – it has a ten-to-one advantage. We would be chopped to matchsticks.'

'But it could be even worse,' Julia said. 'After France fell Churchill ordered the Royal Navy to sink the French fleet in its Algerian ports. But his cabinet overruled him; the Navy was ordered back. And so Germany took the French Navy, one of the most powerful and most modern in the world. What a mistake for the British!'

'Yes,' Josef said. 'They lacked the confidence to strike – or the foolhardiness.'

'The English are all cowards,' Julia said lightly.

That stung Ernst, who had fought the English in the Low Countries. 'And what is it you want, madam, save for the prostration of your own people?'

She was unperturbed. 'On the contrary, it is what I offer him that interests Josef in me, I think.'

Josef grinned. 'Don't think she wants me for my body. I hope that we will soon be engaged in a great enterprise together.'

'What madness are you cooking up now, Josef?'

Julia dug into her canvas bag and brought out a couple of books. 'Do you read English, Ernst? I'm afraid I have no German translations, not yet.'

He fingered the books. One was a battered volume titled If It Had Happened Otherwise, published in 1931, edited by somebody called J.C. Squire. The other was actually a magazine, he saw, with a garish cover; it was called Unknown. It was a year old.

Julia said, 'The Squire book is a collection of essays, speculations on how history might have developed differently if certain key events had taken another course. What if Napoleon had won at Waterloo, for instance?'

Claudine glanced at the book. 'There is an essay here by Churchill!'

'As for the magazine-' Julia tapped the contents page with a manicured finger. 'This is the item of interest.' It was a contribution from an author called L. Sprague de Camp, and it was called 'Lest Darkness Fall'. 'De Camp's serial imagines a man gone back in time to a Rome on the point of falling to the barbarians. What if that collapse could have been averted?'

Ernst clumsily translated the title into German. 'What is all this, Josef?'

His brother clasped his hands behind his head. 'Do you ever have the feeling that history went wrong, Ernst? I mean, everything we do is entirely shaped by the past. If not for our ignominious defeat in the west in the first war, if not for the spiteful settlement of Versailles, we would not be sitting here now – yes? And take that further. What if you could change history so that, for example, Germany did not lose the first war?'

'History developed as it did through necessity.'

Julia sighed. 'Your brother really is rather unimaginative, Josef.'

'Well, I warned you about that.'

Julia said, 'There are plenty of ways things could have gone differently. If the British had been persuaded to stay out of what was essentially a continental war, for instance. If that had been so, the Kaiser could have won, in the sense of achieving his central goal of an economic union of the European peoples centred on Germany. Wouldn't that be a better history than the one we endured? I mean, all those lives lost on the killing fields of France – your own father's invaliding-'

'Be careful what you wish for,' said Claudine. 'If not for the turmoil that followed Germany's defeat, surely you Nazis couldn't have risen to power.'

Josef applauded ironically. 'Well, I don't necessarily agree with your conclusion, but you have the right idea, unlike my brother.'

Ernst shook his head. 'What is the point of this conversation? Even if you wished to change history, you could not.'

'Ah.' Josef glanced at Julia. 'You might think so, mightn't you? But Julia assures me that it is not so. There is a peculiar technology, developed in America-'

'America! I might have known. You have proof of this, I suppose,' Ernst snapped at Julia.

'In fact I do,' Julia said. 'Proof intelligible to a historian anyhow. But I don't yet have the means to deliver an operational technology. There is a component I lack… a human component.'

'Strictly speaking, subhuman,' Josef said.

She smiled at him fondly. 'I am confident that when England is in German hands, that component will shortly be found and brought to me.'