Idiots on every count, not least for using sub-machine guns: the idea surely was to capture Kampmann alive. But worst of all – the kind of basic error Frank wouldn’t have expected of a police cadet in their first week – was their failure to secure the restaurant and stop potential witnesses from leaving. The catalogue of errors continued: the Gestapo left it a day before they examined Kampmann’s quarters at the Luftwaffe base, and a further day before they asked permission to search his office. They had floundered around like this until Christmas, seemed to do nothing for a week, and when they resumed their investigation in the new year, it was to no effect. And now Kriminaldirektor Gunther Frank had to pick up the pieces.

The following morning, he called in the Gestapo case officer, a shabbily dressed man called Manfred Lange with filthy shoes and a dirty raincoat that he kept on throughout their meeting. Frank realised Lange was out of his depth: as far as he could tell, he was really no more than a Gestapo ‘watcher’, someone whose job was to follow people. He’d no doubt been over-promoted as a result of being a particularly zealous Nazi. But Frank knew he needed to be careful. Whenever there was a conflict between a state body like the Kripo and the Nazi Party, the party always won. If he put a foot wrong, he’d be in trouble.

‘So no one thought to keep all the other diners in the restaurant so they could be questioned?’

‘Of course we did!’ As he spoke, Lange revealed a mouthful of misshapen teeth, all of them an unpleasant shade of dark yellow.

‘But you have none of their details.’

‘By the time we returned to the restaurant after the shooting, they’d all gone.’

‘How long did you leave it?’

‘Half an hour.’

‘What about the manager, this… Hoffmann?’

‘He’s a good party member, a loyal and—’

‘Maybe so, but was he able to give you any helpful information?’

The Gestapo man shook his head, aware that he wasn’t coming out of this well. ‘The only other person in the restaurant whose details we have is the waiter, a man called Hinkler. H-I-N—’

‘I can spell Hinkler, thank you.’

Following an unpromising start, Hans Hinkler turned out to be very helpful indeed. A tall, stooped man with a nervous tic and a distrusting air about him, he was monosyllabic for about five minutes, until Franks gave him a cigarette, told him to take off his coat and called him Hans. He wasn’t in trouble, he said, and the Kripo was most certainly not to be confused with the Gestapo, if he could see what he meant.

‘Are you in the party, Hans?’

‘No, sir, but I—’

‘Don’t worry, Hans, nor am I. So perhaps we can be honest with each other, eh?’