Holocaust survivor Eva Schloss - the stepsister of Anne Frank - will be in York later this month for the Festival of Ideas. She spoke to STEPHEN LEWIS

EVA Geiringer was coming downstairs for her 15th birthday breakfast when a knock came on the door.

It was Amsterdam, May 1944. Eva and her mother Fritzi were Austrian Jews who had been hiding from the Nazis for two years. The people at the door were Gestapo.

Eva's mother could think of only one thing to say. "We're not Jewish!" But of course it did no good. "They knew who we were," says Eva - now Eva Schloss - speaking with a calm dispassion 70 years later.

It was the knock they had been dreading for two years, ever since the family had split up and gone separately into hiding. Eva's father Erik and elder brother Heinz had found refuge with a rural family. Eva and her mother, meanwhile, had moved from house to house in Amsterdam, being sheltered by families willing to take them in.

Often, says Eva, a false wall would be built for them to hide behind in case of a search. But when the fateful knock came, there was no hiding place. They had moved in with this family only a week earlier, and there had been no time for preparations.

At first, they had no idea how they were discovered. But when they were dragged off to Gestapo headquarters for interrogation, where they were reunited with Erik and Heinz, it all became clear.

As 1944 ground on, it was becoming more and more difficult for Jewish families to find hiding places. Erik and Heinz were being blackmailed by the people they were staying with. Fritzi arranged, through her contacts, for a house for them to stay at in Amsterdam. "There was a Dutch nurse who said she knew a safe house, which was very, very near us," Eva recalls.

But the nurse was a double agent. "She was really working for the Nazis."

The Nazis waited until Fritzi and Eva paid a visit to Erik and Heinz. "We hadn't seen them for such a long time!" Eva says. "But they (the Nazis) followed us home afterwards, so they knew where we were."

That knock on the door came the very next day.

The family was interrogated for three days. It felt like the end, Eva says. "We really thought these were our last few days on Earth."

They were then put on one of the notorious cattle trucks and shipped off to Auschwitz - though their guards didn't tell them where they were going. The family tried to cling onto some kind of hope, the belief that a miracle might happen.

"It is very, very important not to give up," Eva says.

As it turned out, they were lucky that it was Auschwitz they were bound for. That sounds extraordinary, she admits - but there were places that were even worse.

"Many people went to different camps, such as Treblinka. There, all those transported went straight to the gas chambers."

Auschwitz was a labour camp - which meant there was a possibility of survival. When they arrived, a 'selection' was made. "Half - the very young, the elderly - were immediately gassed," Eva says.

The other half, including the four members of the Geiringer family, were selected for work details.

But first, there was one of those dreadful, heartrending scenes that have featured in so many films. Men and women were separated: families were torn apart. "There were just terrible scenes," Eva says. "People screaming, crying, trying to hold on to each other..."

Eva and her mother both survived the camps. Her father and brother did not.

Even now, 70 years on, she has not been able to forgive the Nazis, she says. Their cruelty went so far beyond the pale. She gives one example. After they had been separated, the new arrivals at Auschwitz were told the other half - including loved ones - had all been gassed. "They told us that with great pleasure," Eva says."They were so cool about it."

After she and her mother were finally liberated by advancing Russians in January 1945, and for several years after, the 85 year old admits that she was filled with hatred: hatred against the Nazis, of course: but also against the Dutch, for betraying her family: and against the US, Canada, Australia and even Britain for not accepting more desperate Jewish refugees, when they must have known what was going on. Britain accepted 10,000 schoolchildren, she says. "But why didn't they take the parents as well?"

Gradually, she learned forgiveness - for all but the Nazis themselves. She came to the UK in 1951 and married her husband Zvi Schloss. She built a life: having three children, working as a photographer and then running an antiques shop. And then, in 1988, she wrote a book: Eva's Story. She has continued writing and talking about the holocaust ever since.

Eva was a childhood friend of Anne Frank - they used to play in the same square in Amsterdam before the worst of the pogroms began. After the war, Eva's mother went on to marry Otto Frank, Anne's father. Later, Eva helped found the Anne Frank Trust UK. "The reason was to speak, to educate young people about how dangerous racism is," she says.

Her most recent book, After Auschwitz, was published as a Hodder paperback in April. And on June 22 Eva herself will be here in York for the Festival of Ideas, to talk first-hand about her experience of surviving Auschwitz, and the desperate search for her father and brother afterwards.

It was only later that she found out they were both dead. And heartbreakingly, her father died knowing his son was already dead, and believing his wife had died too. He thought that, because Eva had told him so.

After she and her mother had been separated from Erik and Heinz, they were sent to a barrack in Birkenau, part of the Auschwitz complex. There they slept 500 to a building, 10 to a five-foot-deep ledge.

Food was a mug of liquid in the morning and a chunk of bread at night. But they survived - partly because Eva herself was tough and because she so yearned to live; and partly because she and her mother were put to work sorting through the clothing of Hungarian Jews who'd been brought to the camp, looking for valuables. It was work which was slightly less exhausting than they could have been given.

Then, in September or October, came a devastating blow. Eva's mother was selected to be gassed. They were separated, and Eva was left alone. "That was the hardest time of all," she says.

Miraculously, some time afterwards, her father managed to arrange to visit his daughter. It was then she told him her mother was dead. "I saw his face crumple."

After that, she believes, he "just didn't want to live. He was a tough, sporty, clever man, 45 years old. But I think he just gave up."

But Eva survived, to be reunited with her mother, who wasn't dead after all - and ultimately to be an extraordinary witness to the atrocities that man is capable of inflicting on his fellow man.

* Life During and After the Holocaust: Eva Schloss talks about surviving Auschwitz. York Festival of Ideas, Sunday June 22, 2pm to 3pm, Berrick Saul Building, University of York. Tickets free: to check availability, visit www.yorkfestivalofideas.com/tickets