Once the weather warmed up, Carla was able to take her turn queuing for food. She carried Walli with her wrapped in a pillowcase – she had no baby clothes. Standing in line for potatoes one morning, a few blocks from home, she was surprised to see an American jeep pull up with Frieda in the passenger seat. The balding, middle-aged driver kissed her on the lips, and she jumped out. She was wearing a sleeveless blue dress and new shoes. She walked quickly away, heading for the von Ulrich house, carrying her little basket.

Carla saw everything in a flash. Frieda was not trading on the black market, and there was no syndicate of doctors. She was the paid mistress of an American officer.

It was not unusual. Thousands of pretty German girls had been faced with the choice: see your family starve, or sleep with a generous officer. French women had done the same under German occupation: officers’ wives back here in Germany had spoken bitterly about it.

All the same, Carla was horrified. She believed that Frieda loved Heinrich. They were planning to get married as soon as life returned to some semblance of normality. Carla felt sick at heart.

She reached the head of the line and bought her ration of potatoes, then hurried home.

She found Frieda upstairs in the drawing room. Erik had cleaned up the room and put newspaper in the windows, the next best thing to glass. The curtains had long ago been recycled as bed linen, but most of the chairs had survived so far, their upholstery faded and worn. The grand piano was still there, miraculously. A Russian officer had discovered it and announced that he would return next day with a crane to lift it out through the window, but he had never come back.

Frieda immediately took Walli from Carla and began to sing to him. ‘A, B, C, die Katze lief im Schnee.’ The women who had not yet had children, Rebecca and Frieda, could hardly get enough of Walli, Carla observed. Those who had had children of their own, Maud and Ada, adored him but dealt with him in a briskly practical way.

Frieda opened the lid of the piano and encouraged Walli to bang on the keys as she sang. The instrument had not been played for years: Maud had not touched it since the death of her last pupil, Joachim Koch.

After a few minutes Frieda said to Carla: ‘You’re a bit solemn. What is it?’

‘I know how you get the food you bring us,’ Carla said. ‘You’re not a black marketeer, are you?’

‘Of course I am,’ Frieda said. ‘What are you talking about?’

‘I saw you this morning, getting out of a jeep.’

‘Colonel Hicks gave me a lift.’

‘He kissed you on the lips.’

Frieda looked away. ‘I knew I should have got out earlier. I could have walked from the American zone.’

‘Frieda, what about Heinrich?’

‘He’ll never know! I’ll be more careful, I swear.’