No one had so much as glanced at it when he took it back to Cologne, where he kept it in a case under his bed at night and carried it round in his briefcase all day, every day, until he managed to get a pass to go to Frankfurt for the weekend. The officer who issued the passes gave him a knowing wink and said if he had any plans – another wink – to take care, and if he didn’t take care then to enjoy it, but remember to see the medical officer as soon as he returned.

By the time Falmer arrived in Frankfurt, he was in a terrible state. He’d not slept for two nights and his stomach was playing up quite badly. As sympathetic as he was to the cause, he wasn’t sure he was the right man for this job. The journey to Frankfurt had been painfully slow. The bus had had to negotiate its way through the damaged streets of the city, stopping frequently as carts carrying rubble moved out of its path. It stopped at the railway station, or at least what remained of it, and when Falmer asked an American soldier where the nearest public toilets were, he laughed at him and said about a hundred miles away.

He walked from the station to the small hotel on Allerheiligenstrasse that was reserved for Americans and other Allied officials. It was the only building in the street that appeared unscathed, and seemed pleasant enough. As he was checking in, an American officer told him that as long as he had dollars, there were a couple of decent cafés near the remains of the main post office, and gave him directions.

The handover was planned for ten o’clock the following morning, the Sunday. As Falmer washed in the stained basin in his room, he wondered what to do with the package in the meantime, eventually deciding to take it with him in his briefcase.

His downfall came in a small bar in an alley opposite the post office. He was in the alley because of what had been on his mind since a colleague had told him that the whole of the centre of Frankfurt was a red-light district, due to the fact that people were so desperate. ‘It’s about the only way they can earn dollars – women and men, even children!’

The first bar was noisy and full of American troops and women old enough to be their mothers, and the second felt so menacing he only glanced into it from the doorway. He spotted the third bar down a cutting off the alley, and it was just what he’d had in mind. It seemed much quieter, and more to the point, it had only men in it. As he edged nervously to the bar, teenage boys began to gather around him. Are you American, sir? Do you have dollars? Buy me a drink, I will let you have whatever you want…