Sitting at her desk in her cramped bedroom in Amsterdam on Wednesday, October 7, 1942, Anne Frank found herself daydreaming of a shopping expedition with her cousin Bernd in Switzerland.

“I imagine that… Daddy gives me 150 guilders… and tells me to buy everything that I need,” she scribbled in her red, check-covered diary. “I set off with Bernd and buy: 3 cotton vests @ 0.50 = 1.50. 3 cotton knickers @ 0.50 = 1.50. 3 wool vests @ 0.75 = 2.25.”

The two-page shopping list she went on to itemise included everything from “warm slippers” and an “ice skating outfit” to rouge, lipstick and books.

Sixty-six years on, a few blocks away from the Basle street where he and Anne used to play as children, Bernd, or Buddy as everyone but his cousin called him, is reeling off a very different kind of shopping list.

“We have just supported an orphanage in Nepal. It is not just for orphans but also for girls who have been saved after being forced into prostitution,” he says excitedly. “We have furnished schools for poor children in India and Africa. In Peru, we helped create a school up in the Andes where the children can learn in the native Quechua rather than Spanish. We have given a lot of money to organisations in Israel,” he adds, before jabbing a finger on the dining table. “But only those who work together with Palestinians.”

A nimble, charismatic 83-year-old, Bernd “Buddy” Elias is a well-known screen actor in Switzerland and Germany. Posters of his theatrical appearances in plays such as The Resistable Rise of Arturo Ui, Brecht’s satire on Hitler, dot the walls of his home. But it is his role as the titular and spiritual head of the Anne Frank Foundation, the Basle-based charity that owns and administers the rights to his cousin’s diary, that is taking centre stage in his life today.

Since its establishment by Anne’s late father, Otto, the foundation has distributed grants, bursaries and donations worth “many millions”, says Elias. Their gifts can range from the few hundred euros needed for a school trip to Auschwitz to the hefty medical bills they meet on behalf of the 100 or so members of the “righteous” – Eastern European gentiles who helped Jews escape Hitler. Yet, impressive though it is, the foundation is only the tip of an iceberg. It is one part of what you could loosely call Anne Frank Inc – a network of international charities dedicated to upholding the principles of the idealistic Dutch schoolgirl. Collectively, each year, they spend at least £5 million on good works, ranging from academic research into racism to helping children affected by gang crime in Brazil; from rehabilitating criminals in British and American prisons to fighting knife crime on the streets of London.

Each charity applies the same rules as Elias when deciding which causes to favour. “If ever we are unsure what to do with the money, we just ask, ‘What would Anna [as he calls her] want?’”

As schoolchildren the world over know, Anne Frank never got to go shopping with her cousin. Despite surviving more than two years in a secret annexe above a factory on the Prinsengracht in Amsterdam with her father Otto, mother Edith and sister Margot, she was arrested by the Nazis in August 1944. She died, aged 15, of suspected typhus at Bergen-Belsen with Margot, some time in February or March 1945, a month before the concentration camp was liberated by the British.

What survived her, of course, was the diary she had nagged her father to buy for her 13th birthday, and in which she recorded her daily thoughts on everything from shopping to Nazism, boys to ice skating. It was given to Otto when he emerged from Auschwitz at the end of the war, the only member of his immediate family to survive. The hold it has placed on the imagination of children and adults alike since its initial publication in Dutch in 1947 has been unbreakable. The Diary of a Young Girl has gone on to become the most enduring and personal memoir of the Holocaust, with sales, according to Elias, fast approaching 40 million copies. It has been translated into more than 70 languages, from Afghan to Welsh, Kazhak to Khmer.

If recent statistics are any indicator, Anne Frank’s popularity among young readers in particular is still growing, and not just in countries such as China and Afghanistan, where translations of the book have only recently become available, in some cases for free. A recent poll found the book was the sixth most popular read among teenagers, just below Harry Potter and Heat magazine but above Tracy Beaker and Katie Price’s pony tales. A heart-rendingly realistic new BBC dramatisation of Frank’s story, adapted by novelist Deborah Moggach and starring Ellie Kendrick as Anne, Iain Glen as Otto and the outstanding Tamsin Greig as Edith, is poised to generate fresh readers. All of which would seem to suggest that, even in an uncertain economic climate, Anne Frank Inc’s remarkable work will continue for a while longer.

The enduring power of the story at the heart of it all is clear to see on a weekday winter’s morning in Amsterdam. Inside what used to be the Opekta factory on the Prinsengracht, where Anne’s father made an ingredient used in jam-making, schoolchildren and groups of adults are politely squeezing their way past the sliding bookcase that hides the entrance to the Frank family’s annexe. Up the steep, wooden stairs, they dwell silently on the photos of Hollywood film stars that Anne pasted to the wall of her room and look out at the chestnut tree that was the only thing visible to her as she wrote in her diary. As they do so, the languages being whispered range from English and Japanese to Spanish and German.

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