The pilot’s intercom was just about loud enough to break through the racket. Because of a strong prevailing wind, he told them, they’d take off in a northerly direction and head up the Øresund, banking south once they reached eight thousand feet. This would take about ten to fifteen minutes; they’d then climb to around nineteen thousand feet, crossing the German coast at Stralsund and heading south, keeping to the east of Berlin and flying close to a maximum speed of around one hundred and sixty miles an hour.

All the passengers had been handed copies of Völkischer Beobachter, the mouthpiece of the Nazi Party. Prince read a long article on the brave defence being put up in Stalingrad. Things must be going badly for the Germans in the battle; anything less than positive in the Völkischer Beobachter usually meant bad news.

An hour later, the pilot was back on the intercom: the wind was against them, he announced. They were descending to fifteen thousand feet and one hundred and thirty miles an hour. They were unlikely to land at Tempelhof before eleven fifteen. He was sure the passengers would all understand.

His final announcement came at eleven twenty: passengers may have noticed they had not landed he said, sounding rather pleased with his little joke. They’d been told by air traffic control to fly as far south as Schönefeld before turning north towards Berlin.

Just before their final descent, a steward came round to check all the curtains were drawn over the portholes. They were not to be opened in any circumstances, he instructed them. Otto Knudsen leaned over and whispered in Prince’s ear: ‘There are military planes here; they don’t want anyone to see them. Especially those bringing casualties back from the east.’

It was a shade before half past eleven when the Junkers Ju 52 pulled off the runway, crossed the apron and shuddered to a halt in front of the arrivals hall. It was a short walk from there to the building, where non-German nationals were pointed in the direction of a separate entrance.

‘Let me go in front,’ said Knudsen. ‘I’ll be talking in German but it’s probably better if you don’t let on you speak or understand more than a few words.’

When it was his turn, Prince was searched and his suitcase emptied on a trestle table where a bored-looking woman in a light brown uniform checked every item. He noticed half a dozen men, presumably Gestapo, spread out around the perimeter of the room, their backs to the wall, observing everyone and everything. He caught the gaze of one of them for a few unblinking seconds. Prince smiled politely and the man continued to stare.