The first time Alwin Meyer visited one of the children of Auschwitz, they were reluctant to let him in because he was German. “A Jewish friend had arranged the meeting, and I realised if he hadn’t been there they wouldn’t have spoken to me,” Meyer tells me now, half a century on from that initial encounter. “At that time, in the 1970s, they couldn’t open the door to a young German. It was impossible for them.”

Now 71, Meyer has dedicated his life to telling the stories of those who survived childhood incarceration in Auschwitz: at least 232,000 minors were sent to the concentration camp, the vast majority of them Jewish, but only 750 were liberated alive at the end of the war, 60 newborn babies among them. Meyer spent years trying to track them all down, winning their trust and recording their memories. It was his way, he says, of addressing an “inheritance” of guilt.

The details he uncovered are harrowing: how, for example, the children in Auschwitz used to play the “gas chamber game”, throwing stones into the ground to represent the people being taken to the crematorium, or discussing how the ovens were built. They would watch adult prisoners end their lives by walking into the electric border fences. Once, 1,500 children were sent to their deaths in a single day.

It is facts like these that make Meyer’s book, translated into English for the first time this month as Never Forget Your Name, so shattering to read. When you’re writing about Auschwitz, where one million people were murdered, it’s easy for everything to become a blur of numbers. But Meyer turns the statistics back into stories: telling us where the children came from, how they survived, and what happened to them after the war.

Sitting at the kitchen table of his flat in central Berlin, a plate of homemade traditional German biscuits in front of him, he describes a life spent confronting the darkest of horrors. Twin brothers Jiri and Zdenek Steiner were 13 years old when they were sent to Auschwitz. Jiri told Meyer how the boys wanted to take their toys with them but “were told, ‘No, you can’t.’ The time for playing was over.” Yehuda Bacon, who was 10 when he was transported to the camp, recalled how “the trains were sealed, like sealing a living person in a coffin. We were treated like cattle being taken to slaughter.”