A film about the Holocaust, on which Alfred Hitchcock was an adviser, will be released at last, reports Francine Wolfisz.

He was called the master of horror and carved a career out of exploring the darkest depths of the human mind. But there was one true-life atrocity which even Alfred Hitchcock could not bear to watch on the silver screen: the Holocaust.

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Women and children concentration camp inmates liberated by the British at Bergen-Belsen in 1945.

Now a forgotten documentary about Nazi death camps, on which Hitchcock was asked to collaborate before the project was shelved for political reasons, is to be screened for the first time after being restored by the Imperial War Museum.

In 1945, the much-lauded director of such thriller classics as Psycho, Rear Window and Vertigo was persuaded by his friend, the Jewish director Sidney Bernstein, to leave Hollywood for England and collaborate on a documentary about German wartime atrocities.

Much of the footage was shot by British and Soviet army film units during the liberation of Bergen-Belsen just months before and, as a “treatment adviser”, Hitchcock had been brought in to help organise the material.

Dr Toby Haggith, senior curator at the Imperial War Museum, says the film was commissioned for propaganda purposes. “Once they discovered the camps, the Americans and British were keen to release a film  quickly that would show the camps and get the German people to accept their responsibility for the atrocities,” he told the Independent. But the footage was unlike anything the renowned American director had seen before. It was reportedly so horrific that Hitchcock was traumatised and stayed away from the studios for a  week.

His contribution to this powerful work is unmistakable, however. In an interview before he died, Bernstein explained how Hitchcock sought to present the footage with the maximum impact. And while he did not travel to Dachau, Belsen and Buchenwald, Hitchcock did provide instruction to the camera crews on taking wide, establishing shots and unbroken panoramas, which would help to prove that the harrowing scenes had not been staged. Bernstein said: “He took a circle round each camp, different villages, different places and the numbers of people – so they must have known about it…

Otherwise you could show a concentration camp as you see them now and it could be anywhere, miles from humanity. He brought that into the film.” According to Peter Tanner, one of the film’s editors, Hitchcock’s concern was that “we should try to prevent people thinking any of this was faked…so Hitch was careful to try to get material which could not possibly be seen to be faked.” In the event, the documentary was never screened for fears it would harm Britain’s post-war relationship with Germany.

The project was canned and five reels deposited at the Imperial War Museum, where they lay undisturbed for decades. In the ensuing years, Hitchcock’s contribution to a film on the Holocaust became a lesser-known fact, though his “Jewish” connections have been well- documented. He had several close and long-standing Jewish collaborators, including his friend and agent, Lew Wasserman, costume designer Edith Head, screenwriter Ben Hecht, composer Bernard Herrmann, producer David O Selznick and graphic designer Saul Bass, responsible for coming up with the shot-by-shot storyboard of the famous shower scene in Psycho.

Hitchcock’s long career saw him pick up many prestigious awards, including two Golden Globes, five Academy Award nominations (although never a win) for best director and a knighthood just before his death in 1980, aged 80. But his little-known film about the Nazi camps was not to remain forgotten. Some 40 years after being consigned to the museum vaults, the footage was stumbled across by a researcher  and an incomplete version shown at the Berlin Film Festival in 1984.

It was also broadcast on American PBS in 1985 under the title Memory of the Camps. Now the film, the title of which has not yet been revealed, will finally be shown as intended. Using digital technology, the museum has restored the work and pieced together extra material from a missing sixth reel. It will be shown at film festivals and cinemas this year and on British TV next year to mark the 70th anniversary of the liberation of Europe.

An accompanying documentary, Night Will Fall, is also being made with Andre Singer, executive producer of The Act of Killing, as director and Stephen Frears as directorial adviser.

Haggith says the restored work will show the true horrors of the Holocaust, but also offer a glimpse of life beginning anew. “It’s an alienating film in terms of its subject matter but also one that has deep humanity and empathy about it. Rather than coming away feeling totally depressed and beaten, people will find there are elements of hope.”