He laughed as she gave a grimace of recognition and he reached for her spare hand, shaking it.

‘What are the chances of that? Sharing a birthday.’ This was, he thought, fate. He was excited, relieved too. Now they had something to talk about. ‘Tell me how people celebrate birthdays in Germany. Do you sing Happy Birthday?’

‘We have a birthday song,’ she said. She opened her mouth. ‘“Hoch soll er leben.”’ Her voice was light and clear, supple as a fiddle. She sang the words. The tune was catchy and he tried to sing with her, a word behind, a beat too late.

‘Perhaps,’ he said, ‘there are songs we have the same, could sing together?’ He liked the idea of singing with her. ‘Ah. I know.’ He opened his mouth, hummed first, then sang. ‘Silent Night’. It took five bars, and she was singing with him, walking round the outer path, in harmony, in step.

‘I have another Christmas song,’ she said. ‘I can teach you all my songs. It’s a good way to learn language. A new way.’ She opened her mouth. He knew this tune too. ‘Twinkle, Twinkle, Little Star’ by any other name.

She turned, her eyes glistening, as if the music had lifted a weight, breathed life and energy into her. ‘This is fun,’ she said. ‘Let’s sing.’

He wondered what else to sing. The school had had a good choir, but the repertory was classical. Even the folk songs were composed. He wasn’t sure he wanted to start on the Messiah, or the St Matthew Passion. Seemed a bit sombre for a first encounter. He turned, checked. Arthur was a discreet distance behind them.

‘I have a song,’ she said. ‘We would sing it as children.’ He’d seen film of the Hitler Youth on the Pathé newsreel at the cinema before the war. He could hear the commentator: These happy boys and girls are marching to the ‘Horst-Wessel Lied’. Raise the flag, they sing, the ranks tightly closed! They certainly put our Boy Scouts to shame… Had she been a member of the Hitler Youth, or whatever the girls’ equivalent was? Perhaps this was not such a good idea.

‘Muss i denn…’ she began. ‘Muss i denn…’ Hand on her heart. He wanted to reach out, to catch her crystal voice and let it echo in his memory, to hold her hands and draw her close. She was wonderful, this young woman, swathed in sadness and enigma. Perhaps love felt like this.

‘Tanz mit mir, Johann?’ She stopped singing, put down her bag with the jug. She curtsied, held her skirt wide and pointed her foot. He could see how she arched it, even inside the shabby lace-up shoes with the flapping sole. Her eyes were glassy, her cheeks flushed.