Having that conversation in front of him had been their first mistake, the first of a number the Gestapo made that day. The second was throwing him in a cell with someone else in it, a boy around eighteen years of age with a mop of blonde hair and a large bruise under one eye that he wore like a badge of honour. He told Prince he’d been arrested for throwing an apple core at a German armoured car. Prince told him he had no idea why he’d been arrested: a misunderstanding over his legitimationskort perhaps. He wasn’t even sure where he was.

‘This is the main police headquarters on Polititorvet. At least they’ve brought you here. If they offer you an all-expenses stay at the Gestapo place on Kampmannsgade, turn them down.’ The boy came and sat next to him on his bench and spoke quietly in a conspiratorial manner. ‘Do you have anything to worry about?’

‘I’m not sure what you mean.’

‘I mean, you say they arrested you over your legitimationskort. Was that at a checkpoint?’

‘Yes.’

‘And did they arrest anyone else?’

‘Not as far as I could tell.’

‘And your identity… do you have anything to be concerned about it? I mean, is it genuine?’

At Matlock they’d told him to be careful of plants, seemingly sympathetic people who’d appear to be your friend, on the same side, and who’d lure you into revealing too much. With his innocent looks and obvious pride in his bruise, the boy didn’t look like a plant, but Prince knew he couldn’t risk it.

‘Of course it’s genuine – why wouldn’t it be?’

Perhaps they’d realised their mistake, because soon after that, he was moved to another cell, this time on his own. It was tiny, lit only by a small amount of daylight diffused through the opaque window. The darkness and the solitude gave him time to reflect. He remembered Gilbey’s warning – The Gestapo see through most cover stories, sooner or later – and realised he needed to act fast.

His opportunity came half an hour later, when he was marched up two floors and into an empty interview room, one not wholly dissimilar to the ones he’d spent so much of his career in. A Danish policeman guided him to a chair on one side of a large wooden table and secured one part of his handcuffs to the side of the chair.