The Cut Out Girl is the gripping tale of a Jewish girl who escaped the Nazis, written by her saviours’ grandson. Here, author and heroine talk about their life-affirming collaboration

‘I must tell you a secret,” Lien de Jong’s mother said to her gently one day. “You are going to stay somewhere else for a while.” It was August 1942 in occupied Holland and De Jong was eight years old. The family was Jewish, but not observant. She would never see her parents again; they were murdered in Auschwitz six months later. She was sent to live with a non-Jewish family, the Van Eses, the first in a series of temporary homes in the Netherlands’ wartime underground network.

Bart van Es is a Dutch-born English literature professor at Oxford University, who usually “writes scholarly books and articles on Shakespeare and Renaissance poetry”. He is also the grandson of Jans and Henk van Es, who, as part of the Dutch resistance, sheltered Jewish children such as Lien de Jong during the occupation. His account of her extraordinary, harrowing story of loss, survival and love, The Cut Out Girl, has just won the Costa Book of the Year award.

“I was very amazed,” 85-year-old De Jong says, laughing, the morning after the ceremony. “I thought the young lady would win.”

“Sally Rooney,” Van Es supplies.

It is true that Rooney’s much-talked-about second novel, Normal People, was the hands-down favourite to take the prize. But The Cut Out Girl was “a hidden gem”, according to Sophie Raworth, chair of the Costa judges. “It was the book we felt everyone should read.”

“I think of it as very much a joint book,” Van Es tells De Jong.

Arrestingly and simply told, The Cut Out Girl is a powerful addition to memoirs of the Holocaust. It is a whiplash jolt from Rooney’s knowing story of millennial love and angst. “There is something millennial about this, too, in a way,” Van Es suggests. “It’s about modern Europe as well as about the war.” The book interweaves De Jong’s story with Van Es’s travels around the Netherlands – wartime archives, railway and petrol stations, motorways – during which he was struck by the impact of far-right politics there today, with figures such as Geert Wilders of the Party for Freedom (PVV) making headlines. “He’s had very significant votes and has really changed the tone of Dutch politics in quite a scary way,” Van Es says.

Play Video 1:56 Bart Van Es’ The Cut Out Girl named Costa Book of the Year – video

Famed for its tolerance, the Netherlands has “also got its nasty side”. Returning to his grandparents’ house, in what is now an almost entirely Muslim area, he says he felt uncomfortable researching a Jewish story. “It made me think, there’s a danger now that the world is becoming compartmentalised again in echo chambers of people who just tell their own stories. This is a story in one way about a non-Jewish person talking to a Jewish person, but beyond that about a person from the 21st century looking back at the 20th century.” If there is a message to the book, he says, it is that “you have to look beyond yourself, you have to have some larger vision, because in the war the people who acted, who did something for the Jews, were largely people who were part of organisations that spanned racial divides, things like my grandparents being part of the socialist movement.”

“They were very principled people,” De Jong says. “They didn’t accept injustice in any way.”

Although he “always had this sort of background idea, that I’m the family academic and I ought to write this up,” there wasn’t one single trigger that prompted Van Es to begin researching the life of the “lost” Jewish girl who lived with his grandparents during the war, but with whom there was a mysterious rift many years later. He has no memories of De Jong, although she remembers him as a tiny child, and he refers to her as “Aunt” in the book. “I like to say that,” he says, when I ask how they like their relationship to be described.

“I never thought about it. You can call me Aunt,” she responds fondly.

What was meant to be just a cup of coffee and a sandwich with his “aunt” turned into a 10-hour conversation and then a month-long extended interview, in which he came to know her “in a way that I had never known anybody else. Even with your most intimate contacts, you would never normally say: ‘Tell me your life, your earliest memories; what was your room like when you were a little girl?’ It was just an astonishing privilege to have that with another human being. I think that is something that has changed me. It has made me a more empathetic person.”

Facebook Twitter Pinterest De Jong in July 1945. Photograph: Bart van Es

Of their first exchange, De Jong says: “I always thought, ‘I have no special story, so what do you want?’ But talking together, it became a story.”

And what a story it is. Her time with the Van Eses, which she refers to as “my first hiding parents”, was a particularly happy one. “That was the only place where I felt safe and could be a child and play with the other children,” she says. But then the knock would come on the door. “It’s funny how much shoes would matter in the time of crisis,” Van Es observes in the book, as she would have to pull on whatever was available and literally run for her life. The succession of hideouts that followed were increasingly unhappy, as she was passed from family to family, treated as a servant in one, and sexually abused in the last.

It is striking in the book how De Jong’s memories, so vivid at first, become more vague as she becomes more traumatised. “One of the things the book is about is that you only remember things if you experience them in a community,” Van Es says. Towards the end of the war, De Jong became “almost like a zombie … She lived just in herself, living that was just living; she suddenly starts having these enormous gaps where she remembers absolutely nothing.”

This, of course, presents something of a challenge to the biographer. And it is here that Van Es pulls off a clever authorial sleight of hand, making De Jong’s story intensely immediate and intimate, only then to concede that she herself can’t recall the details at all. “I wanted to be honest about that,” Van Es explains. “I wanted that sort of trick in the book, so you see it and then you don’t see it. And so I wanted those things to be completely historically correct, which they are. I did research.” For example, during the mass exodus from the village of Bennekom in 1944, a procession of families laden with their belongings, or piled on to carts and wagons, we see the bodies of fly-ridden dead horses and soldiers lying in bomb craters, and are told that De Jong “feels sticky” under the three dresses she is wearing to avoid carrying them. But as Van Es admits: “Of the journey to Ede … she can picture nothing at all.” Instead, he has “patched together” the recollections of the hundreds of others who made the journey, taken either from history books and diaries, or from accounts of people he later interviewed.

“So it’s not necessarily Lien wearing three dresses. I will always make it clear that’s a made-up bit.” He wanted it to be not just factually accurate – he even checked the weather reports in newspapers from the time – but also “emotionally true”.

How does it feel for De Jong, after all these years, to have the gaps filled in by someone else?

“The emotional part is not there anywhere. It’s history for me, the whole story,” she replies. “Sometimes I’m sad about my family, who were lost, all of them; most of the time it is in a movie or on TV – just looking at other people I can feel emotion.”

Today, she says, she is happy “with my friends and children and grandchildren”. She loves Amsterdam, where she lives, and enjoys being part of its cultural life. “I hope very much that my story can help when we are talking about children who are in a terrible situation these days, without parents or without family, going from one country to another,” she says.

On the day of the Dutch publication of the book, which also happened to be De Jong’s 85th birthday, they appeared on a TV chatshow. The discussion centered on two Armenian children who were due to be deported back “home” in two days, despite having spent their whole lives with Dutch foster parents and speaking only Dutch. “It was really shocking that the government was saying: ‘We are going to send these children back,’” says Van Es. The following day a decision was made to allow the children to stay. “I had at least the right to speak,” she says, modestly denying Van Es’s reports that people on Twitter were saying DeJong had done more than those in parliament to help. The book sold out in the Netherlands the next day.

This is not just a deeply personal story, for both De Jong and Van Es, but also one of national guilt: 80% of the Jews in the Netherlands died during the war, more than double the proportion of any other country in western Europe. With a bounty on every Jewish head, the Dutch authorities delivered 107,000 Jews to the death camps. “It is absolutely shocking,” Van Es says. “There was massive national hypocrisy at the end of the war. There were virtually no prison sentences for any of the collaborators and there was very little national reflection. Although it is changing now, for a very long time it has just been a straightforward story that: ‘We were occupied and essentially we were all part of the resistance.’”

Against that background, Van Es recounts stories of extraordinary heroism and desperation: the farmer who cut off part of his finger in order to get paid leave so he could build a secret shelter for children; or the couple who turned their food-testing laboratory into a safe house, saving 50 children, with the help of a local doctor, but whose own lives ended in depression and poverty; or the family who sheltered in a hideout beneath a tree in a pine forest, breathing by means of a hand-pump connected to the ground above them.

But The Cut Out Girl doesn’t end with De Jong’s return to the Van Es household after the war. There can be no uncomplicated happy ending. After a period of stability, in which she married and had three children, De Jong felt like “a cut-out picture of a perfect wife from a magazine”. She became increasingly depressed and isolated from her husband, whose traditional Judaism was “not very meaningful” to her. “I couldn’t live with it,” she says. In 1972, she attempted to kill herself.

“I don’t think I had survivor’s guilt,” she reflects. “It was more the idea that I did not – I ought not – to be there. There was nobody who wanted me. When you have no family of your own, and you live with people who can send you away, no connection is unbreakable.”

Facebook Twitter Pinterest Van Es with De Jong at the Costa ceremony. Photograph: Henry Nicholls/Reuters

Life healed her, she says: “And the children and my choices. It took time.” At 47, she got divorced. “I married a very good man. But he couldn’t come along after a long time. I didn’t know what I wanted.”

And then there was another terrible fracture, when Jans van Es – the woman she once called “Ma” – cut her off, the family mystery that is the emotional heart of the book: “Why, at my grandmother’s funeral, was Lien unmentioned and unseen?” Van Es asks. “How could such a connection break?”

To answer this would be to give too much away. But the book has been healing for Van Es’s family. His mother, who was terrified about what its revelations might do to her parents’ reputation as brave members of the resistance, has been comforted by its reception. As Van Es says, winning the Costa has been an “incredible confirmation of what was quite a scary enterprise. Quite a lot of people have said they think it’s a kind book. So it was really uniting.”

It has also been uniting for his immediate family, in particular for him and his teenage stepdaughter, Josie. De Jong’s experiences of feeling unwanted taught him “how important it is to tell people all the time: ‘You matter to me.’ It gave me a really good chance to talk to Josie. It has been a very meaningful thing for our family.”

“Nobody is perfect,” De Jong adds. “We can see in the book that you can be a human being with all your faults and all your good things.”

Van Es is already at work on another book, if not closer to home, then closer to his academic interests, on Shakespeare and the novel. And De Jong? “Just going on.”

There are so many books already out there about the war, Van Es worries at one point. “There are also so many songs about love,’” De Jong replies.

The Cut Out Girl: A Story of War and Family, Lost and Found by Bart van Es (Penguin Books, £9.99). To order a copy go to guardianbookshop.com. Free UK p&p on all online orders over £15.