The British had had four years to arm themselves for this invasion. Most of the German army was fighting Russia. Once the Allies got a toehold on French soil they would be unstoppable. The Germans' only chance was to catch them on the beaches and annihilate them as they came off the troop ships.

If they were waiting in the wrong place, they would lose that one chance.

The whole strategy was immediately clear. It was simple, and it was devastating.

Faber had to tell Hamburg. He wondered whether they would believe him.

War strategy was rarely altered on the word of one man. His own standing was high, but was it that high?

That idiot Von Braun would never believe him. He'd hated Faber for years and would grab at the opportunity to discredit him. Canaris, Von Roenne… he had no faith in them.

And there was another thing: the radio. He didn't want to trust this to the radio… he'd had the feeling for weeks now that the radio code wasn't safe anymore. If the British found out that their secret was blown…

There was only one thing to do: he had to get proof, and he had to take it himself to Berlin. He needed photographs.

He would take photographs of this gigantic dummy army, then he would go to Scotland and meet the U-boat, and he would deliver the pictures personally to the Fuehrer. He could do no more. No less.

For photography he needed light. He would have to wait until dawn. There had been a ruined barn a little way back; he could spend the rest of the night there.

He checked his compass and set off. The barn was further than he thought, and the walk took him an hour. It was an old wooden building with holes in the roof. The rats had long ago deserted it for lack of food, but there were bats in the hayloft.

Faber lay down on some planks but he could not sleep. Not with the knowledge that he was now personally capable of altering the course of the war. Dawn was due at 05:21. At 04:20 Faber left the barn.

Although he had not slept, the two hours had rested his body and calmed his mind, and he was now in fine spirits. The cloud was clearing with a west wind, so although the moon had set there was starlight.

His timing was good. The sky was growing perceptibly brighter as he came in sight of the "airfield."

The sentries were still in their tent. With luck, they would be sleeping. Faber knew from his own experience of such duties that it was hardest to stay awake during the last few hours. But if they did come out, he would have to kill them.

He selected his position and loaded the Leica with a 36-frame roll of 35mm fast Agfa film. He hoped the film's light-sensitive chemicals had not spoiled; it had been stored in his suitcase since before the war, and you couldn't buy film in Britain nowadays. It should be all right; he had kept it in a lightproof bag away from any heat.

When the red rim of the sun edged over the horizon he began shooting. He took a series of shots from different vantage points and various distances, finishing with a close-up of one dummy plane; the pictures would show both the illusion and the reality.

As he took the last, he saw movement from the corner of his eye. He dropped flat and crawled under a plywood Mosquito. A soldier emerged from the tent, walked a few paces, and urinated on the ground. The man stretched and yawned, then lit a cigarette. He looked around the airfield, shivered, and returned to the tent. Faber got up and ran.

A quarter of a mile away he looked back. The airfield was out of sight. He headed west, toward the barracks.

This would be more than an ordinary espionage coup. Hitler had had a life of being the only one in step. The man who brought the proof that, yet again, the Fuehrer was right and all the experts were wrong, could look for more than a pat on the back. Faber knew that already Hitler rated him the Abwehr's best agent. This triumph might well get him Canaris' job. If he made it.

He increased his pace, jogging twenty yards, walking the next twenty, and jogging again, so that he reached the barracks by 06:30. It was bright daylight now, and he could not approach close because these sentries were not in a tent but in one of the wall-less huts with a clear view all around them. He lay down by the hedge and took his pictures from a distance. Ordinary prints would just show a barracks, but big enlargements ought to reveal the details of the deception.

When he headed back toward the boat he had exposed thirty frames. Again he hurried, because he was now terribly conspicuous, a black-clad man in the open fields of a restricted area. He reached the fence an hour later, having seen nothing but wild geese. As he climbed over the wire, he felt a great release of tension. Inside the fence the balance of suspicion had been against him; outside it was in his favour. He could revert to his bird-watching, fishing, sailing role. The period of greatest risk was over. He strolled through the belt of woodland, catching his breath and letting the strain of the night's work seep away.

He would sail a few miles on, he decided, before mooring again to catch a few hours' sleep.

He reached the canal. It was over. The boat looked pretty in the morning sunshine. As soon as he was under way he would make some tea.

A man in uniform stepped out of the cabin of the boat and said: "Well, well. And who might you be?"

Faber stood still, letting the icy calm and the old instincts come into play. The intruder wore the uniform of a captain in the Home Guard. He had some kind of handgun in a holster with a buttoned flap. He was tall and rangy, but he looked to be in his late fifties. White hair showed under his cap. He made no move to draw his gun. Faber took all this in as he said, "You are on my boat, so I think it is I who should ask who you are."

"Captain Stephen Langham, Home Guard."

"James Baker." Faber stayed on the bank. A captain did not patrol alone.

"And what are you doing?"

"I'm on holiday."

"Where have you been?"

"Bird-watching."

"Since before dawn? Cover him, Watson."

A youngish man in denim uniform appeared on Faber's left, carrying a shotgun. Faber looked around. There was another man to his right and a fourth behind him.

The captain called, "Which direction did he come from, corporal?"

The reply came from the top of an oak tree. "From the restricted area, sir."

Faber was calculating odds. Four to one until the corporal came down from the tree. They had only two guns: the shotgun and the captain's pistol. And they were basically amateurs. The boat would help too.

He said, "Restricted area? All I saw was a bit of fence. Look, do you mind pointing that blunderbuss away? It might go off."

"Nobody goes bird-watching in the dark," the captain said.

"If you set up your hide under cover of darkness, you're concealed by the time the birds wake up. It's the accepted way to do it. Now look, the Home Guard is jolly patriotic and keen and all that, but let's not take it too far. Don't you just have to check my papers and file a report?"

The captain was looking a shade doubtful. "What's in that canvas bag?"

"Binoculars, a camera, and a reference book." Faber's hand went to the bag.

"No, you don't," the captain said. "Look inside it, Watson."

There it was, the amateurs.

Watson said, "Raise your hands."

Faber raised his hands above his head, his right hand close to the left sleeve of his jacket. Faber choreographed the next few seconds; there must be no gunfire.

Watson came up on Faber's left side, pointing the shotgun at him, and opened the flap of Faber's canvas bag. Faber drew the stiletto from his sleeve, moved inside Watson's guard. and plunged the knife into Watson's neck up to the hilt. Faber's other hand twisted the shotgun out of the young man's grasp.