On 25 June 1947, Anne Frank’s diary was first published, going on to become a much-loved bestseller worldwide. In this exclusive archive clip, her father, Otto, tells the BBC about his decision to make her words public.

Otto Frank initially couldn’t bear to read, let alone publish, his daughter’s diary, which was released 57 years ago this week. In 1976, he travelled to the BBC’s Blue Peter studio to explain why he did. “I only learnt to know her really through her diary,” Otto Frank confessed to Blue Peter’s Lesley Judd, as he showed her the personal writings of his beloved late daughter Anne.

Otto had actually given his bright, outgoing daughter an autograph book as a gift for her 13th birthday on 12 June 1942. But Anne had almost immediately decided to use it as a diary and began to record her innermost thoughts, writing as if she was revealing secrets to a close friend. “I hope I shall be able to confide in you completely, as I have never been able to do to anyone before,” Otto read out from Anne’s first diary entry on the children’s TV programme. “And I hope you will be a great support and comfort to me.”

Otto had fled with his family to Amsterdam in 1933 from Frankfurt, where Anne had been born, following the Nazi Party’s success in the German federal elections and Adolf Hitler being appointed Chancellor of the Reich. But the safety the Dutch capital seemed to offer from the looming threat of the Nazis would prove to be only a temporary reprieve for the family. In 1940, Hitler having now seized power and declared himself Führer, invaded the Netherlands. With German occupation came a wave of antisemitic measures. Jews were prohibited from owning businesses, forced to wear identifying yellow stars and faced curfews.

Otto, like many Jews, had been attempting from 1938 to emigrate to the US, but the lack of an asylum policy, and the lengthy process to acquire a visa, meant that the paperwork couldn’t be completed before the Nazis shut US consular offices in all German-occupied territories in July 1941.

A month after Anne’s birthday in 1942, Otto’s older daughter Margot received a call-up notice to report to a German labour camp. To evade the authorities, the whole family moved into a secret annex Otto had discovered above his business premises in Amsterdam. For the next two years, the Frank family hid in that space, along with another family and a family friend. In the stifling confines of the annexe, everyone living there was forced to remain silent during the day, and were unable to use the toilet until night-time when the office cleared, for fear of being heard. Food and supplies were smuggled in by a small group of trusted helpers.

All this time, Anne kept scribbling her thoughts in her diary in secret. Because of her longing for friends her own age, she invented fictional characters, such as Kitty, to write to. Her anxiety, aspirations and boredom, along with the routine frustrations of living so tightly cooped up with other people, were all laid out on her diary pages.

The last entry is on 1 August 1944. On the morning of 4 August, the Gestapo stormed the hideout and all the occupants were arrested. The reason for their discovery is still disputed.

The Franks were taken to Auschwitz-Birkenau concentration camp where Otto was separated from his wife Edith and daughters Margot and Anne. He would never see them again. All three would perish in the camps. Anne, who along with her sister was eventually transferred to the Bergen-Belsen concentration camp, died of typhus in March 1945 just weeks before the camp was liberated.

Otto was the only member of the annexe to survive. After the war, he returned to Amsterdam to search for his family, only to be devastated when he learnt of their fate. Anne’s diaries and letters had been rescued from their ransacked hiding place by his friends Miep Gies and Bep Voskuijl, who were able to give them to him on his return. But in his grief, he could not bear to look at them at all. “I don’t have the strength to read them,” he wrote to his mother in Switzerland on 22 August 1945.

When Otto could finally bring himself to open the diaries, the writings were a revelation to him. They offered him a window into the mind of his clever, vulnerable and expressive teenage daughter as she navigated the complexities of adolescence in the most terrifying of circumstances. In unvarnished tones, they detailed her clashes with her mother and her resentments toward her sister, her worries about her reputation and her changing body. They also revealed how oppressive she found the confinement and silence of the annexe, and her palpable irritation with the people she was living with. She wrote of her isolation and the constant terrifying threat of their discovery. How she felt like “a songbird who has had his wings clipped and who is hurling himself in utter darkness against the bars of his cage”.

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But Otto got insight into her small moments of joy, too: the nature she glimpsed through her window and her budding romance with Peter van Daan, the boy who also lived in the annexe.

She wrote of her dreams of skating in Switzerland and ambitions to be published; her thoughts about her identity and her relationships with friends, both real and imagined.

He began to gain an understanding of Anne’s complex and imaginative mind as it changed and matured. “I wouldn’t be able to write that kind of thing anymore,” she wrote of one of her earlier diary entries. “Now that I’m rereading my diary after a year and a half, I’m surprised at my childish innocence. Deep down I know I could never be that innocent again, however much I’d like to be.”

Most of all, Otto got to appreciate Anne’s gift as a writer, and the extraordinary courage and humanity she had in the face of the unrelenting terror of their circumstances. “After I had read the diary, I copied it and I gave a copy to friends of ours who had known us all,” he told BBC’s Judd in 1976. “One of them was employed in a publishing firm and he told me ‘you have not the right to keep the diary as a private property, it’s a human document and you should publish it’. And so I did.”

On 25 June 1947, The Secret Annexe, a book compiled from Anne’s diary entries and writings, was published. As well as correcting some of her language mistakes, Otto sanitised it somewhat, editing out some of Anne’s critical impressions of his marriage, passages about her sexuality, and her sometimes savage portrayals of people she knew.

The book proved to be an instant success, a single girl giving a face to the almost incomprehensible horror and magnitude of the Nazis’ genocide. In 1952 it was published in English under the title Anne Frank: The Diary of a Young Girl. It was made into a Pulitzer Prize-winning play in 1956, and a film three years later. Anne’s words have far outlived her short life; they have been translated into more than 70 languages, and continue to resonate with readers worldwide.

Asked by Blue Peter’s Judd if he had any reservations about agreeing to publish and reveal his daughter’s most private thoughts, Otto Frank said: “I didn’t regret it because Anna wrote in one of her diaries ‘I want to go on living after my death’, and in a certain way through her diary she is living on in many hearts.”

In History is a series which uses the BBC’s unique audio and video archive to explore historical events that still resonate today.

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