‘Come and have dinner, I’ll cook Bresse chicken. You don’t hold any grudge against Bresse poulet, do you?” The man on the phone didn’t need to give his name. Claude Lanzmann never introduced himself; he didn’t need to.

I came to know him in 2013 when I started the research on my latest book, Left Bank: Arts, Passion and the Rebirth of Paris 1940-1950. I wanted to meet the “survivors” of that era before they disappeared. What an extraordinary introduction to my subject. Lanzmann, then 87, was very much still at the centre stage of life and intellectual discourse, and an extremely busy man.

He had just finished editing The Last of the Unjust, which was about to premiere at the Cannes film festival. It told the complex and controversial story of Benjamin Murmelstein, one of the Jewish elders used by the Nazis as concentration camp administrators and the only one to have survived the war. Hated for being a collaborator, Murmelstein nevertheless saved many lives through his negotiations with Adolf Eichmann.

It was Lanzmann at his finest: using some of the 350 hours of unseen footage he shot for his groundbreaking nine-and-a-half-hour long documentary Shoah in order to highlight the inexplicable, with both force and subtlety. Shoah, both an important historical document and an original work of art, was based on hours of testimonies both from survivors of the concentration camps and former Nazis whom he filmed secretly, as well as Polish villagers living near the camps of Treblinka, Chelmno, Auschwitz and Birkenau. Polish antisemitism was so starkly demonstrated by Shoah that Warsaw demanded the film be banned after its premiere in Paris.

Murmelstein was the first interview of hundreds that Lanzmann carried out for Shoah between 1974 and 1980, before embarking on a five-year editing process. He didn’t make the cut. “Shoah was epic and told a relentless tragedy. Murmelstein had no place in it,” he told me. “If I had included him, Shoah would have had to be 20 hours long.” In the past 20 years, Lanzmann did go back many times to the unused footage of Shoah in order to make other documentaries: A Visitor from the Living, Sobibór, The Karski Report, and, this year, Four Sisters: Baluty, a four-part documentary series. The portrait of sisters who survived the Holocaust was released in France last week, on the day before he died.

Lanzmann, like his friend and mentor Jean-Paul Sartre, was a workaholic. He worked fiercely and tirelessly until the end. There was neither place nor time in his life for idleness, indulgence, complacency or, indeed, any sort of compromise. Death must have taken him by surprise. He loathed death; it made him very angry. Why did you have to die when, like him, you still had so many things to do? “Death is an absolute scandal,” he used to say.

Death must have taken him by surprise. He loathed death; it made him very angry

Lanzmann had many projects. Cinema was very important to him, and so was writing. A great writer, he lately thought of building on the success of his memoir, The Patagonian Hare (published in English in 2012), which sold half a million copies in France. “I have many more things to say and reveal,” he said.

Lanzmann lived in a two-bedroom flat near the Montparnasse cemetery. He had found it in a rush in the early 1970s as he embarked on Shoah. He never meant to stay. Forty years later, he was still there.

Lanzmann liked receiving his guests in his kitchen, probably unchanged since the 1950s. The day we had Bresse chicken, I brought a bottle of Vacqueyras and some cherries. His 19-year-old only son, Félix, who lived with his mother in the flat below, helped him cook and set the table with a beautiful white damask tablecloth and assorted napkins.

Félix, a gifted philosophy student, died last year of cancer at the age of 23. This tragedy profoundly shook Lanzmann, yet he confided in his last interview with Paris Match: “Despite it all, I still believe in life, it is in me, so deeply rooted. I am so fundamentally alive, I don’t consider myself old or in need of slowing down. When I look at myself in the mirror, I don’t feel I look shrivelled.” He didn’t.

We met a few times, walked down rue de la Bûcherie where he lived with Simone De Beauvoir, with whom he had a liaison throughout the 1950s. We talked in his living room, facing south, always bathed in a luminous glow. His living room was no place to relax; the walls, desk, leather sofa and glass coffee table disappeared behind and under books, press cuttings and magazines. In the little space left on the shelves were framed pictures, many of De Beauvoir and Sartre.

I eventually found out that Lanzmann was not much interested in reminiscing about his youth or the past. He was too busy living the present to the full.

Whenever he called, he would say: “Come, I have much news to share with you.”