Walking around Kendal Mountain Festival last November I noticed that every other person was wearing an Atom LT Hoody from Arc’teryx. Kendal is arguably the biggest indoor outdoor event in the country, the only place to be seen outside the mountains, and we must spend more time in front of the mirror over that weekend than the rest of the year combined, preening to our rugged and garish best. With unbeaten pedigree, myriad colours and an uncanny ability to straddle the lines between smart, casual and superlight Alpine, the Atom LT is the perfect choice for adventurous social occasions. But it must be more than a pub jacket, right....? I bought one to find out (and partly, to fit in...)

I‘ve long been a fan of synthetic insulation but I don’t buy the prevalent idea that it will replace the humble fleece; it’s just not breathable enough. Maybe not a problem in the depths of winter, but as soon as energy levels rise the synthetic becomes way less versatile than fleece. Arc’teryx have solved this problem by stitching stretch fleece side panels down the full length of the jacket, and it’s this design element that makes the Atom LT stand out by massively increasing breathability, mobility and bulk.

In January the thermometer in Tignes varied between +9 in the village to -10 in the wind on the glacier and the Atom LT did a good job of regulating my temperature tucked under a shell. I was way too hot skiing the chopped up off piste lower down the valley, but then I always am. Walking in the snowy Lake District it is a perfect throw-on for pit stops – and barely noticeable once it’s back in the pack. Winter climbing is where the Atom LT excels; for me the amount of insulation is usually warm enough on the belay, and the breathable panels allow enough heat to escape when the terrors push your heart rate. It means I can keep it on for the whole route, without (usually) the belay-stance-costume-change routine.

So unless you need a classic belay jacket – which it’s not meant to be – I’d say the Atom LT has got the warmth/weight ratio spot on. What else has it got? A clever little waterproof strip along the hem stops moisture wicking up into the jacket, a helmet compatible hood (naturally) and my favourite thing; some kind of supernatural face fabric. It looks like it has the integrity of used tissue but it stands up to abrasion that should shred it to pieces and it beads light rain remarkably well (and is still doing so after several months.

Perhaps best of all, it doesn’t really have any other features. It’s brilliantly sleek. It’s minimal without being miserly. No wonder it’s a classic. The Kendal crowd are as discerning about gear as they are films!

Reviewed by Daniel Wildey for The Epicentre