Things became more hectic when they reached the edge of German territory. A single-file column of armour almost a kilometre long stood along the road awaiting orders to advance. The tanks were wide and Henderson had to pass slowly, often with a set of wheels running in the grass verge.

The fields beside the tanks were dotted with exhausted French troops. The Germans had captured more than a million French soldiers during the early part of the invasion. But guarding prisoners was a drain on German manpower and feeding them practically impossible. So while French prisoners in the north had spent the past month penned into fields, dying from disease and starvation, soldiers captured now were simply stripped of weapons and equipment and ordered to march south.

The ones who remained were injured or sick and had no option but to suffer in the sun without even water, while their enemy calmly waited to be resupplied before pushing onwards. Marc had seen plenty of suffering during his journey from Beauvais to Paris, but the sight of young soldiers dying of thirst and hunger seemed especially chilling. Beyond this human wreckage, another field was piled high with orderly stacks. Tin helmets, rifles, ammunition, grenades.

Henderson managed a smile. ‘When I was a boy, I had a collection of lead soldiers,’ he said. ‘Before I went to bed, my mother would make me tidy them all up into piles, just like that – only smaller.’

The thoughts of childhood made Marc realise that he knew nothing about Charles Henderson. ‘Do you have a wife or children, sir?’

‘I had a daughter, but she died of tuberculosis when she was a baby. My wife took the loss very badly.’

‘I’m sorry,’ Marc said, shifting uncomfortably in his seat and wishing he hadn’t asked.

‘She broke down completely at one point,’ Henderson admitted. ‘We’d like another child, but my spending so much time abroad makes that difficult.’

After passing through a village crowded with German troops, they came to a fork and Henderson picked a dirt road that obviously wasn’t the main highway. The lane twisted and trees overhung from either side, creating a dappled shade.

‘I think we’re past the last of the Germans,’ Henderson said, driving as quickly as he dared.

Marc dived off his seat when they came to a clearing from which an artillery piece aimed straight at them. Henderson realised that they were French.

‘Marc, get up and hold the wheel,’ he shouted frantically, remembering that he was still wearing a German tunic and pulling it down his arms.

As Marc steered, the French soldiers began to shout and Henderson slowed down. It was fortunate that they’d taken one of the commandeered French trucks, because a German army vehicle would have caused outright hostility rather than suspicion.

‘Lean out of the window so they can see you’re a child,’ Henderson ordered.