Be prepared for visit 16–20 February: it will be on a night when there’s a full moon.

Essential you remain in the camp.

Trassenheide will be spared.

Afterwards you will gather as much information as possible on impact of visit: regard this as a priority and an instruction!

When this task complete, you may leave the camp.

I will be where I dropped you every Sunday, Tuesday and Friday starting 48 hours after the raid between 2–4 p.m. Meet me there.

There was little to reassure him in the message, not least its lack of subtlety. Peenemünde was to be bombed, which came as no surprise. But he’d somehow assumed he’d be given ample warning and would be able to escape before the raid. That Trassenheide was to be spared was of little consolation. Even if it was, gathering intelligence on what damage had been done was going to be perilous in the extreme – and Sophia’s escape plan sounded more fanciful than anything else.

He wondered whether to mention anything to Émile, but realised it was too risky. Although he’d grown close to the group of French workers in his hut and they knew what he was up to, he couldn’t be sure he’d trust them enough once they became aware of the raid.

The 16th was a Tuesday and it didn’t look like a full moon, so he decided to remain in the hut that night. But on Wednesday, the moon certainly seemed rounder and brighter. He feigned a bad stomach that evening, which was feasible enough given the pitiful food they received: all the prisoners in the hut next to theirs had a type of dysentery, and they’d been told that some of the Russians further up the camp had died from malnutrition. He kept his work clothes on and stayed in the toilet block behind their hut all night. He did the same thing the following night, and it was then that the raid happened.

Many of Prince’s childhood Sundays had been spent on long, bracing walks across fields that went on for ever in the Lincolnshire countryside. Apart from the mud, the silence and the vast skies, his enduring memory was of enormous murmurations of starlings flocking above them, twisting and turning in an intricately choreographed display. They’d bumped into a farmer one day who, like them, was watching the display with awe.

‘Now then, lad, how many birds do you think there are up there?’

‘A thousand… two thousand?’

The farmer shook his head and bent down to let him into a secret no one else should hear. ‘Over one hundred thousand: there’re more starlings above us now than there are people in the whole of Lincoln!’

That was his abiding thought once the raid began: the bombers like a flock of starlings, dark shapes merging as one mass, twisting and turning in the moonlit sky, menacing and fascinating at the same time.