For a while those labourers who had escaped the fires were corralled in their own area by a small number of very nervous guards, but they were then marshalled into groups to go into the main part of the camp to help fight the blazes.

Prince tried to make a note of where they were and what damage he could see, but it was near impossible to make much out in the darkness and the confusion. They’d spend a few minutes fighting one fire before being hurried to another then waiting to be given another task. They spent several hours carrying bodies to a makeshift morgue near the airfield, and as dawn broke, the extent of the damage began to become apparent.

It was hard to know what kind of detail London wanted. The majority of buildings did appear to have been hit, but only a few had been completely destroyed. There was even evidence in the experimental area of work continuing as normal, and he saw a large rocket – apparently unscathed – being mounted on what looked like a railway wagon.

Later that morning, he was allocated to a small work detail in the main barracks area, where the Germans lived. One housing block had taken a direct hit and two others were damaged, but the destruction was not as extensive as he’d hoped. As they were helping to clear a roadway, a young SS officer came over to them. His face was ghostly white and he was trembling as he lit a cigarette. Prince smiled and held the match for him. He was amazed when the officer offered him one.

‘Where are you from?’ He sounded grateful to have someone to pass a few moments with.

‘France, sir.’

The officer nodded, as if to confirm that he’d heard of France.

‘Which part?’

‘Lyon, sir.’

‘My cousin is based there. You speak good German.’

Prince couldn’t quite believe how uncharacteristically placid the SS officer was. This was the perfect opportunity to find out what he knew.

‘How many people were killed last night, sir?’

The German shrugged. ‘How the hell would I know? Hundreds, certainly.’ He nodded in the direction of the destroyed housing block. ‘All of them in there, for a start.’

‘Were there soldiers or scientists in there?’

Now the officer looked a bit more suspicious. ‘Why are you asking?’

‘I was just wondering. The airfield looked intact, but the V-2 works seemed to have taken a few direct hits…’

He’d misjudged the situation: the officer was no longer placid. ‘Why the hell are you asking all these questions?’

‘I know why he’s asking all these questions.’

Prince turned round to see who’d spoken. It was another French prisoner, one from a hut a little way away from theirs. They were a group from Blois whom Émile insisted were not to be trusted: Pétainists.

‘Why’s that then?’ The SS officer had walked over to the man.