Jonathan Salt is a non-Jewish teacher from a Peterborough Secondary School who is a world away from all the nasty headlines about the Edinburgh Fringe and a certain comedian. This righteous gentile is at the same festival reminding audiences about what antisemitism can lead to.

His show, Confessions of a Butterfly, has attracted five-star reviews and it is not surprising.

A desperately poignant and yet also inspiring one-man play which he wrote and stars in, Salt gently tells the story of children’s rights advocate and orphanage director Janusz Korczak during his final 24 hours in the Warsaw Ghetto.

Salt has been fascinated by Korczak, whose heroism is still largely unknown in the UK, for nearly twenty years, since a youth theatre he was involved with staged a musical about him.

Jonathan Salt plays the Polish-Jewish director of the orphanage

“His ideas about children were so forward-thinking and are still relevant today. There was so much to his story that I wanted to do more with it,” he recalls. At an exhibition about the Jewish hero who refused entreaties from his non-Jewish friends to abandon his children and hide, he met Korczak biographer Sandra Joseph who helped inspire him to create a one-man show about the pioneer.

Jonathan is someone who takes his work seriously. He pored over Korczak’s diaries and travelled to Poland to learn about him. He is a Holocaust and genocide educator and uses theatre to teach the lessons of the past.

“He was brought up in a very secular Jewish family. His father died when he was only 16 – we think he committed suicide – and his mother also died when he was a young man after catching typhus. He was a paediatrician and an inspiring character, who wrote books for children and for adults. He even had a radio show on Polish national radio. He was a celebrity but was also a campaigner for children’s rights, both in the way they were treated within the criminal justice system and as an educator.

“He ran two orphanages – a Jewish one and a Catholic one. When the Nazis invaded, wealthy Polish Catholics said they would help him escape but he didn’t want to leave his children so he went into the ghetto with them.”

In Confessions of a Butterfly, we meet him when he knows the Nazis are about to start rounding everybody up and put them on trains to Treblinka, where they would be murdered. At that point Korczak had 200 children in his care. Every morning, he would go around the ghetto with a big sack pleading for food for them.

“We don’t whether he knew what would happen, he doesn’t write this down. But there is a sense that something dreadful is going to happen. He knows that deportations are happening. I think the idea that the Germans would kill 200 children was an anathema to him. But what could he do to stop it?

“It is a question that often comes up in school during our lessons on the Holocaust. The children want to know why the Jews didn’t fight back. Well, they did in the ghetto but you also have to look at what sort of position they were in. They were starving – Korczak was surviving almost solely on alcohol mixed with water because it was the only way he could get calories.”

Korczak did fight in his own way; even as the Germans liquidated the ghetto, he led his children, head held high, singing.

 At a time of soaring antisemitism, it is an interesting time to put on a show about the Shoah and shortly before taking the show to Edinburgh, Salt put the show on at his school which has a high Muslim population.

“I was very nervous because I haven’t performed it in a school where I was a teacher before, I wasn’t sure how they would react to it,” he says. “But I had the most fantastic feedback from the children. And a teacher who is fiercely pro-Palestinian sent me this email saying how moving and important the play is.”

In the course of writing the work, Salt has also come across another inspiring teacher. Damas Gisimba was an orphanage boss during the Rwandan Genocide and the children he cared for were a mixture of Hutu and Tutsi. Salt interviewed Gisimba and has written a book about him called The Lion who Roared in the Dark.

These two brave men, these educators and leaders, are his inspiration. “The message has to be that we have to teach children to love. We cannot teach them to hate.”

Confessions of a Butterfly is at Green Side Venues at the Edinburgh Fringe.