Richard Riddiford discusses his documentary, Before Everest.

In his last autobiography, Sir Edmund Hillary wrote of fellow mountaineer Earle Riddiford: ‘I’d never share a rope with him’.

It’s perhaps the most damning thing one climber can say about another and the slur prompted Riddiford’s children – documentary maker Richard and his sister Anna – to ask: ‘What do you do when the man on the $5 note disparages your father?’

Their film, Before Everest, traces the origins of the slur to divisions that developed during New Zealand’s first expedition to the Himalayas in 1951 which Riddiford organised and invited Hillary to join.

You started making the film in 2000. Why did it take so long to finish?

It was difficult because we didn’t want it to come across as a carping film about Hillary. We wanted it to be a celebration of my father’s journey.

And yes, it’s Edmund Hillary, that was a difficult subject to traverse. My father’s old climbing group were not keen to be seen to be negative about that story.

In the documentary, Hillary is shown to be not that generous when it came to acknowledging other people’s contributions and perhaps this is why he made those remarks about Earle. Do you feel you got to the truth of Hillary’s comments?

I think we did. In the beginning, we were worried about what it was [that led Hillary to disparage Earle], whether it was some terrible thing and where we could go with that. But about halfway through the story we finally got to the point where it’s actually not really about my father. Hillary’s remark is more about him than my father. That was a good realisation to have.

How do you think the film will be received by New Zealanders?

Most people are conflicted and cynical about politicians, journalists and most public figures but Hillary is someone we can unreservedly be proud of, so I suppose some people won’t be happy we are calling into question what happened. But, as I say, we are not trying to be negative or derogatory about Hillary in any way, it’s just putting the record straight in terms of what happened, how those events [in 1951] unfolded and trying to give that story a place in history.

Has your opinion of Hillary changed through the process of making the documentary?

No, and we never sought to take anything away from Hillary. He was an extraordinary human being who created such a legacy for New Zealand. But we did want to put the story straight. If my father hadn’t organised the 1951 expedition, there’s no way Hillary would have got on the British expedition in 1953.

You make no bones about the fact that you disliked your father. Why was your relationship so fractious?

Often mountaineers are driven, extremely uncompromising and determined people and my father was no exception. He had many positive points but he was also very difficult because he was so uncompromising to get along with. In a family situation that can make life very difficult.

By the end of the film, you seem to have more positive feelings towards Earle.

I think that was part of my journey – to get to the point where I could celebrate what extraordinary things he did do. Even though I began it feeling I really didn’t want to go down that track due to my own personal situation of him not being that great and I felt slightly hypocritical that I suddenly turn around after he was dead saying what a great guy he was. Gradually, that evolved into something where we could see what he did achieve and separate it from my own personal feelings and then come out feeling very positive about the whole thing.

Do you now feel more comfortable with your relationship with your father?

I think I do. I have grown up children of my own now and it felt great to show them what he did and what is possible and what an extraordinary legacy he created for our family. It is something that they can look up to and be a guide in their life of what you can do.

Beyond Everest will be screened at the New Zealand International Film Festival between July 24 and August 2.