British actress Helena Bonham Carter speaking with a Jewish woman whose family escaped Czechoslovakia with the help of the actress’ grandmother, Violet Bonham Carter. Photo: Screenshot/”My Grandparents’ War.”

British actress Helena Bonham Carter discovered new details about the heroism of two grandparents during World War II in a new four-part docuseries that debuted Sunday on PBS.

In the premiere episode of “My Grandparents’ War,” Bonham Carter, 54, learned about her paternal grandmother — an air raid warden and politician who spoke out against the rise of Hitler and Fascism in the 1930s — and her maternal Jewish grandfather, a Spanish diplomat who saved thousands from the Holocaust.

Bonham Carter’s grandmother, liberal politician Violet Bonham Carter, was the daughter of a former prime minister and close friends with former UK Prime Minister Winston Churchill. She helped Jews from across Europe seek refugee in Britain and campaigned against antisemitism, Helena discovered. The British actress, who played Princess Margaret on The Crown for the past two seasons, met a descendant of a family Violet helped escape from Czechoslovakia, and the survivor shared letters between her parents and Violet.

Helena also saw speeches Violet gave in the 1930s — including a speech at the UK’s Royal Albert Hall, in which she voiced solidarity with the Jewish community amid War War II and slammed the British government for not doing more to help Jewish refugees. As a result of her outspokenness, Violet was put on the Gestapo black list to be arrested and executed in the event of a German invasion. Helena also learned that during the Blitz of 1940–41 in London, Violet remained in the city as a volunteer air raid warden when other citizens fled.

On her Jewish mother’s side of the family, Helena’s grandfather, Eduardo Propper de Callejón, was a Spanish diplomat in Paris during WWII who defied government orders and issued exit visits that helped thousands of people escape Nazi-occupied France in 1940. The travel visas allowed people to cross safely into neutral Spain and then make their way to Portugal and, ultimately, the US. He was punishing for defying orders by being sent to an outpost in Morocco.

In 2008, he was recognized by Yad Vashem as Righteous Among the Nations for his role in saving Jews in the Holocaust.

In Sunday’s episode, Helena met a woman whose Polish Jewish family was saved by the Spanish travel visas. She still had travel documents with the handwriting of Helena’s grandfather, and revealed that one of her ancestors saved by the visas went on to create UNICEF.

“One thing I think about when I often think about the Holocaust is how much was destroyed. But then, the tiny consolation prize is that you meet the one life that was saved,” Helena said. “It’s almost like one humanitarian act breeds a whole genealogy; a whole tree of other humanitarian acts. When you see his signature on a visa it’s exciting, because it brings him back again and makes it real. Makes the myth real.”

Propper de Callejón’s daughter and Helena’s mother, Elaina, said, “[Eduardo] never talked about what he achieved in his life, he was extremely modest. I remember my mother telling me in the evening that she had to take hot water, put a lot of salt in it, and ask my father to put his hands in it because they were so exhausted and crippled by how much he’d been signing, with both hands. But he never spoke about what he’d done.”

The actress encouraged everyone to dig into their family trees. She said, “We carry our grandparents and what they did inside us. They have a lot to teach.”

“I’m so proud to now know that both Eduardo and Violet in the face of strong oppression stood up for what they believed.”