Of the 6 million who died in Nazi concentration camps during the Second World War, 1.5 million were children. And while pre-war attempts to ship out the the sons and daughters of Jews, communists and other imperilled ethnic and political groups from Germany mostly ended in failure, Britain offered a haven to some of these young refugees.
While the scale of the tragedy that was to engulf Europe's Jews was, as yet, unimagined, other factors prevented large-scale evacuation. In the autumn of 1939, the American Congress threw out a proposal to transport 20,000 children, and other countries were reluctant to admit large numbers of immigrants, especially as the the Nazis had decreed that these mostly Jewish children could take no valuables with them.
The Kindertransport scheme was the lifeline by which 10,000 mostly Jewish children were ferried to Britain in trains and boats in the year before war broke out. They were spared the worst effects of the war, but they suffered separation from their families, and a sense of guilt and responsibility towards those left behind.
Their stories have been explored in theatre (in Diane Samuels's play Kindertransport, which reached the West End in 1996, for instance) and in work in schools in which Kindertransport survivors have participated.
A documentary film, Into The Arms of Strangers, opens today at selected cinemas. It was made with a sense of urgency as the Kinder are now elderly men and women. One potential interviewee in Australia died before filming started, while Norbert Wollheim, a German social worker who instigated the Kindertransports, died five weeks after being interviewed. Wollheim's tragedy was that he failed to get his own family out of Germany - his wife and son died in Auschwitz.
But this is not a film about war or tragedy. If anything it is about human resilience, about people whose stories were buried for 50 years and surfaced only after a Kindertransport survivor, Bertha Levinson, set up the Kindertransports Association in London in 1989.
The greatest proportion of the film's budget was devoted to scouring the globe for archive footage. Some of its most dramatic images come from home movies - rare footage of a synagogue burning on Kristallnacht (November 9, 1938, when synagogues and Jewish shops throughout Germany were systematically destroyed), family scenes shot in happier times, and, finally, the sad farewells on railway platforms. Child survivors, rescuers, parents and foster parents tell their stories, with linking narrative by Dame Judi Dench.
Producer Deborah Oppenheimer, who works in television in the US, wanted to tell the story of her late mother, a Kindertransport child called Sylva Avramovici from Chemitz in Germany. Since making the film, Ms Oppenheimer has come to recognise her own place in history.
"I didn't set out to make this film for the Jewish community," she said at the London Film Festival's gala screening earlier this month. "I believed it was a spectacular drama with all the elements and all the characters and turning points of any great book, or movie of any book I've been attached to. The bottom line was to tell a remarkable story that nobody had heard - that had an appeal across the board. It's about children separating from their parents, and everybody can understand that."
In the film, the former Kinder become child-like when they recall memories of past times, memories they had long buried until they started to meet in Kindertransport groups in their late fifties and sixties. Some, such as Deborah Oppenheimer's mother, were sent to hostels and internment camps when they arrived in Britain rather than placed in host families. To survive the forced separation from her home and family, she focused on her education and her Jewish religion.
Even those who were relatively happy in their new circumstances faced emotional difficulties. Kurt Fuchel, sent to England from Vienna at the age of seven, recalls that for many years he felt guilty that he hadn't suffered enough. When he arrived in England in the late 1930s he was placed with a British family in Norwich, whom he came to love, and threw himself into studying at school. After the war he discovered that his parents were alive in France.
"It came as a bit of a shock," he recalls. "My English foster father persuaded them to wait a year so I could finish the English school certificate. I'd worked hard to be assimilated in England, then suddenly I had to go to France, England's traditional enemy, where they ate frogs' legs. That was the point of view of France at the time, and it was very traumatic, almost more traumatic than to go to England with lots of other children in the same boat."
The reunion had its complications. "My parents let go of a seven-year-old and got back a 16-year-old. I couldn't even speak with them as I no longer spoke German, and I've never been able to re-learn it. In the long run I came to love my parents again."
Mr Fuchel, who now lives in New York, is remarkably positive about his past. The first US vice-president, then president, of the Kindertransport organisation, he has also had a successful career as a computer scientist. "After the war," he says, "most people wanted to get back to normal lives, to start families and careers. Their experiences were pushed into the background, which happens after a tragedy."
The survivors, says Deborah Oppenheimer, "were not looking to complain about their experience. They wanted to forget it publicly, but never privately or emotionally."
Ursula Rosenfeld, from the small German town of Quakenbrueck, arrived in Britain at 13 with her elder sister, Hella. Their father was murdered after being taken to a concentration camp on Kristallnacht, and they were placed in an orphanage in Hamburg. In England they lived with a widow in Brighton. Ursula remembers being frightened of her because she seemed old (she was in her late fifties) but growing to appreciate her kindness.
Ursula stayed in England after the war, had three children and fostered three more, which she says made her understand the sacrifices her own foster mother had made. She later became a magistrate in Manchester. Hella married a German Jewish journalist and returned to Germany after the war, where the couple became human rights activists.
Ursula attended the premiere of Into the Arms of Strangers in London but was reluctant to watch it with her children, because they would have been learning many things for the first time. "I never talked to them in great detail about what happened to me. Now I want them to know. They've turned 40 and are established in their own lives and can cope with it. I want them to know about their grandfather. It was an important part of my life, but when I used to start talking about it they'd say, 'Mummy, those were the olden days', and that was it. That was very hurtful to me."
Perhaps the film's most compelling story is that of Lory Cahn, who was 14 when she boarded a train that was leaving Breslau in Germany for England. The train was already moving when her severely disabled father pulled her off; he couldn't bear to part with her. Lory accompanied her parents to Theresienstadt concentration camp (the first of seven camps she spent time in during the war) but she survived, and later married an American soldier sent to liberate the camps.
"Her father survived too and they had 20 more years together," explains Deborah Oppenheimer. "Lory would have had the opportunity to ask him about pulling her out of the train but she chose never to question him about it. In spite of everything she suffered, she felt she understood the decision, being a mother herself."
Into the Arms of Strangers, certificate PG, is on limited release from today. See local listings for details. Holocaust Memorial Day is on January 27