Emmy award-winning film-maker Andre Singer and historian Simon Schama have endorsed the Holocaust educational work of JRoots and the charity’s increasing focus on combating Shoah denial.

Four-hundred JRoots supporters at the Apollo Theatre in London’s West End on Sunday watched segments from Mr Singer’s documentary Night Will Fall, featuring harrowing footage of liberated Nazi death camps shot by British and American army photographers.

In a subsequent debate, Mr Singer said it still shocked him “that political expediency can so override an obvious moral imperative of exposing what happened 70 years ago. That’s what’s terrifying about [the footage in the documentary] being put under the carpet and stuck on the shelf for so long.”

Mr Schama said: “We are living in a time when truth itself cannot be taken for granted; empirical evidence cannot be taken for granted.

“We once thought the web would deliver us from untruth and would bring everybody together. It took us a long time to realise that the web is the perfect nest of fantasy, demonic fantasy. You can have communities that are nourished by the mutual supply of lies.”

He urged his audience “to go out into the street and the rest of the world and be warriors for truth”.

The event also saw the premiere of a biographical film about 88-year-old JRoots guide and Auschwitz survivor Leslie Kleinman, #8230 A Legacy of Love.

Mr Kleinman, whose Auschwitz number was 8230, returned to the death camp site seven times last year as a guide on JRoots tours.

“JRoots do not take people to Poland to talk about death and sadness,” he said. “They talk about life and life that can still be. I have seen thousands and thousands of Jews be connected in their own way to the Jewish story as a result of what JRoots does. And they have allowed me to connect with my past as well.”