Sir Peter Jackson's restoration of old World War I archival footage has almost proved to be too good.

Britain's Imperial War Museum expressed concern that viewers of the Kiwi's film-maker's upcoming documentary They Shall Not Grow Old would think many of the scenes had been staged.

In order to create the hour-long documentary, which will debut at the London Film Festival on October 16, before screening on the BBC on November 11, Jackson removed scratches, sharpened, images, changed film speeds, colourised the footage and made it 3D.

"What took me totally by surprise is how the faces of the men come alive," the 56-year-old told Empire magazine. "The people become humans again, not these Charlie Chaplin figures."

Colourisation is just one of the many things Sir Peter Jackson has done to Imperial War Museum archival footage for his World War I documentary They Shall Never Grow Old.

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Approached by the Museum to create something original from their extensive archive of footage, Jackson's aim was to create "something authentic" – the life of a soldier on the Western front, what he ate, felt, thought. "It was purely about human experience."

He said he was helped by the fact that dozens of feature films were shot during the 1914 to 18 conflict ("It was like a World War I franchise").

"We also found a trench raid, You can always tell combat footage because the cameraman is behind sandbags trying to stay alive."

HAGEN HOPKINS/GETTY Sir Peter Jackson told Empire magazine that he wouldn't exist if it hadn't been for World War I, and his father had heard good things about Kiwi soldiers during the conflict.

For audio, he took advantage of the BBC archives which included 500 hours of interviews about for 1960s TV series The Great War.

"We use 120 different veterans and they are incredible. There's no self-pity. Just matter-of-fact guys with a lot of humour."

Jackson also revealed that if it hadn't been for that war, he might not exist.

"My dad only emigrated to New Zealand and met my mum because he'd heard good things about Kiwi soldiers in that war."

A New Zealand release or broadcast date has yet to be confirmed for the documentary.