At the beginning of August, we had a funeral for Rupert in Scotland. And then, as executor, I set about sorting out his estate. Nothing really prepares you for going through somebody’s life in papers, especially now everything is digital.

I found Rupert’s book on a backup drive that he had made the day before he left for the Himalayas. When I saw how much there was of it, I thought, “My God!” There were thousands of words, the chapter outlines and character reviews. I couldn’t cope with reading it at that point; I’d get to it later.

Everything changed at the memorial we held for Rupert at a Scottish church in west London on what would have been his 50th birthday, on September 24, 2019. Everyone thinks their brother is special, but seeing more than 300 people from different parts of his life, all with stories to share about him, made me realise the effect he had on so many.

After so many of his friends had asked me about his book, I knew that I couldn’t leave it hidden away. And so I printed off hundreds of pages. At first, I could only read one chapter before I had to put it down for a few weeks, and then I read the second and then the third. It was Rupert’s voice, his vocabulary, his wry observations.

After the first few chapters, it was a mess of gaps. It was about 80 per cent there. The last two chapters were missing, and there was no clue as to how Rupert meant to end it. There was a title, though, White Dog.

On the advice of a friend, I approached a publishing house, Whitefox, which said that one of its authors, John McDonald, was intrigued by the challenge of finishing the book. To do so, I said he would need to get inside Rupert’s mind, to understand how he thought. Rupert would never do something just for commercial purposes – it had to be right.

While it’s tempting to try and read the original and the finished book in parallel, I think the end result is very true to Rupert’s original manuscript. He loved art, and his book is about the art world’s dark underbelly; he didn’t like the way art had become a commodity. He’d laugh because I’m the least literary person. I’m a scientist. But, genre-wise, I’d say it’s a literary thriller.

So much of what one does after a loved one dies is miserable. Selling his flat and sorting his things out. Rupert wasn’t a material person, but having his book published in a readable way means his friends and family can have something of his now, something more meaningful than any possessions. But most of all it’s about having his voice stay around.

You could never have written an ending for Rupert. He often talked about the fact he never wanted to be old. So I do take some comfort in the fact he was doing something he absolutely loved, with a group of people, and probably having the time of his life. Rupert was not a professional mountaineer, but he knew there were risks.

His philosophy of life is worth holding on to. The connection he managed to have with so many people is, you realise, what makes life worthwhile. And I’d much rather think about that than what happened on the mountain.

White Dog by Rupert Whewell is published by Whitefox Publishing

As told to Boudicca Fox-Leonard