To encounter an adult bull musk ox in the winter is one of the great sights of the natural world. In size and texture, these beasts offer a visual overload to match any animal I have photographed. Straight out of a winter fairy tale, they are a cross between a Rastafarian and a large bison - a potent cocktail - and fitting that this colossus of an animal can be extremely dangerous.

The challenge for any filmmaker is to get close enough to do justice to their primeval features. I first tried near the tiny airport base of Kangerlussuaq in Greenland but was never able to get within 200 yards. Then I tried in Dovrefjell, Norway where some of the most acclaimed winter filming work has been done with the species. I did better, but again, on my visit, proximity was a real issue.

Our desk research finally led us to the Yukon in Northern Canada where there seemed to be more practical opportunities. In conjunction with local conservationists, we worked on a plan to allow me to film from the floor of a four-wheel drive jeep, powerful enough to navigate the snow caked terrain. There was no chance of me getting out of the car with these beasts, they have charged and killed photographers in the past.

My wish was to work in a snowfall to add to the sense of winter and in so doing glorify the musk ox’s toughness. This is not a portrait for the summer; we are emphatically north of the Wall in Game of Thrones. During my first 48 hours in the Yukon, there was no snowfall, so I merely observed and plotted.

When caked in snow, as was the case that one snowy morning in the arctic Canada, they look like medieval monsters of the north. Or maybe this would indeed be the first sight we see when entering Hell’s Kitchen. Hopefully we will never find out, but in the meantime, I am fond of this vignette as it prompts me to celebrate the extraordinary world in which we live. It is reality, not fantasy.