Cigare shrugged. ‘We’ll see.’

Lloyd said in French: ‘You can leave now, if you wish. Everything is set.’

Legionnaire did not reply. He was not going to miss the action. For the sake of his prestige and authority he had to be able to say: ‘I was there.’

Cigare tensed, peering into the distance, the skin around his eyes creasing with the effort. ‘So,’ he said cryptically. He raised himself to his knees.

Lloyd could hardly see the train, let alone identify it, but Cigare was alert. It was moving a lot faster than the previous one, Lloyd could tell. As it came closer he observed that it was longer, too: twenty-four carriages or more, he thought.

‘This is it,’ said Cigare.

Lloyd’s pulse quickened. If Cigare was right, this was a German troop train carrying more than a thousand officers and men to the Normandy battlefield – perhaps the first of many such trains. It was Lloyd’s job to make sure neither this train nor any following passed through the tunnel.

Then he saw something else. A plane was tracking the train. As he watched, the aircraft matched course with the train and began to lose height.

The plane was British.

Lloyd recognized it as a Hawker Typhoon, nicknamed a Tiffy, a one-man fighter-bomber. Tiffies were often given the dangerous mission of penetrating deep behind enemy lines to harass communications. There was a brave man at the controls, Lloyd thought.

But this formed no part of Lloyd’s plan. He did not want the train to be wrecked before it reached the tunnel.

‘Shit,’ he said.

The Tiffy fired a machine-gun burst at the carriages.

Legionnaire said: ‘But what is this?’

Lloyd replied in English: ‘Fucked if I know.’

He could see now that the engine was hauling a mixture of passenger coaches and cattle trucks. However, the cattle trucks probably also contained men.

The plane, travelling faster, strafed the carriages as it overhauled the train. It had four belt-fed 20mm cannon, and they made a fearsome rattling sound that could be heard over the roar of the plane’s engine and the energetic puffing of the train. Lloyd could not help feeling sorry for the trapped soldiers, unable to get out of the way of the lethal hail of bullets. He wondered why the pilot did not fire his rockets. They were highly destructive against trains or cars, though difficult to fire accurately. Perhaps they had been used up in an earlier encounter.

Some of the Germans bravely put their heads out of the windows and fired pistols and rifles at the plane, with no effect.

But Lloyd now saw a light anti-aircraft battery emplaced on a flatbed car immediately behind the engine. Two gunners were hastily deploying the big gun. It swivelled on its base and the barrel lifted to aim at the British plane.

The pilot did not appear to have seen it, for he held his course, rounds from his cannon tearing through the roofs of the carriages as he overhauled them.