Peter Jackson has revealed his dislike for filming on set.
The director of the Lord Of The Rings and The Hobbit films said the real pleasure begins when he starts to edit footage.
He was given ample chance to do this on his latest project, They Shall Not Grow Old, a documentary using footage from the Imperial War Museum archive and audio from the BBC’s archive to tell the story of life on the front line during the First World War.
Marking the first centenary of the conflict, it was co-commissioned by 14-18 NOW, the UK’s arts programme for the anniversary, and features footage that has been painstakingly restored and colourised.
Jackson told the Press Association: “It’s a very different process because it was a film where I didn’t have to direct any footage.
“Normally in a movie you write a script, I never wrote a script for this, and you go out and shoot a movie, but I never shot a movie.
“It was all just footage that someone else had shot for me, on a battlefield 100 years ago, so it was really a cutting room film and it happens to be my favourite part of the process.
“I don’t like shooting on set, I don’t like dealing with all that, but I love when we get to the cutting room.
“I sigh with relief, that is when I’m in my element in film-making, when I’m in the cutting room. So this was perfect for me really, in that way.
“The shoot is just a pain in the arse, basically.”
The film is dedicated to Jackson’s grandfather, who fought in the First World War and died in 1940.
The director, 56, said: “I never met him but I used to hear a lot about him and I have had a long interest in World War One and read books, watched documentaries.
“When I was invited to make the film with the Imperial War Museum… all I could think of in my head is every documentary I have ever seen on World War One, and I didn’t want something that had already been done anyway, so it took me a little while and I went back to New Zealand and I thought about it.
“But the fixed idea that popped into my head was, ‘I wonder how we could restore this film’.
“I still didn’t know what the actual film was but I wanted to have a look and see how well we can restore it with all the computer firepower, and I was amazed.
“They send me, like, four minutes just to test and I couldn’t believe how good the results were.
“I literally cried and almost fell off my chair when I saw it because it’s just extraordinary, it looks like modern film and this was just black and white to black and white.
“Still in black and white it looks like it was just shot yesterday, and so what comes from the restored film is the faces of the soldiers and then you actually see them as people.
“Suddenly you don’t have these slightly Charlie Chaplin sort of cipher figures, you actually see them as human beings so that then led to the idea that maybe this is a story of humans and not the war itself, just the human beings.
“So sort of one thing led to the other and I thought the only audio we should have is actually the voices of the people that fought there, so the BBC supplied a lot of tapes that they recorded in the 1960s.
“They were very vibrant guys who were speaking very freely of their experiences and so we ended up with 600 hours of audio to listen to and 100 hours of film and then it formed itself and led the film to be coloured out of the human experience of being in the war.”
They Shall Not Grow Old will have its world premiere at the BFI London Film Festival on October 16, attended by the Duke Of Cambridge, and will be screened simultaneously in 250 cinemas across the UK for one night only.