John Porter and his friends pioneered a more risky type of alpine climbing in the 70s and 80s. One of the mountain ranges they were climbing was Annapurna in Nepal, which has claimed the most climbers' lives of any mountain range.
"I wanted to write about the generation that nearly climbed itself into extinction because that's the sad reality of it. Of that generation probably more than 50% were actually killed in the mountains and I'm kind of one of the survivors and no-one else is going to write a book so I guess it came down to me."
Alex MacIntyre was one of them. In 1982, a stone fell from a mile above him, striking him on the head and knocking him to his death. His friend, John Porter, watched through his camera lens.
One Day as a Tiger tells the story of what they were trying to achieve.
"One day as a Tiger is a Tibetan saying, which basically goes, 'it's better to live one day as a tiger than a lifetime as a sheep' and that was the epitaph on Alex's memorial stone. It was a perfect description of Alex. He was only 28 when he died but he lived absolutely to the maximum extent in everything he did."
They pioneered a faster, lighter way of alpine climbing. It was more risky because it meant taking less equipment so you could ascend the mountain faster.They set the tone for what climbing would become and the investment in better technology.
"You weigh up what you need to get up it in terms of equipment, food, days out and you go for it. And most of the time it worked. We did some amazing climbs so it was about adventure, about freedom, about getting to know people really well in a very intense situation. When you're young, you know, when you're in your 20s / early 30s you don't really think about the consequences, when you have challenges as we did as great as those."
John looks from the benefit of hindsight at the risks they took, which he admits he wouldn't make now that he has children. He still climbs and walks in the Cumbrian fells.
But although the book acknowledges the dangers, it doesn't dwell on them. It is a book about a triumph to achieve their goal of a breakthrough in climbing style.
"Doug Scott says that you die either because you have too much ambition in the mountains or too much bad luck. I think that's a good way of putting it, however, when you're trying the things that we were trying, you're right at the top end of ambition to begin with, so you're trying the unknown and anything which is unknown is going to throw up some surprises."
John Porter and his friends climbed Annapurna's south face in 3 days in the 80s, knocking a month and a half off the record. 30 years later a new generation is even lighter and faster. Swiss alpinist Ueli Steck climbed it in 28 hours in 2013.
"Alex predicted the coming of Ueli Steck. I mean I didn't believe him - we used to have arguments. He said, 'people would be flying into Base Camp in helicopters, they'll be phoning home, they'll be watching themselves on TV' - this was back in the 70s and 80s - and I said, 'don't be silly Alex, that's never going to happen'. And he said something very prophetic, he said, 'we're aiming to climb the Annapurna South Face in about 3 days, which is going to knock a month and a half off the best time, but in the not too distant future, some lad's going to come along with a completely different approach, with a different set of equipment, that's going to make our stuff look archaic and with an understanding and a fitness which is beyond our comprehension'... and of course that was Ueli Steck who climbed the South Face of Annapurna in 1 day in 2013. I think Alex would have been delighted to see the changes in climbing: it is now much more sociable, it's more fun, it's safer, it is a heck of a lot more comfortable and I think he would have liked to have been part of that."
John's next book will be another survivor's tale of the friends he lost for the climbing we know today.