Omni-Heat 3D Knit Crew II Base Layer Top, Columbia, £70, columbiasportswear.co.uk

This space-age undergarment employs Columbia’s Omni-Heat technology to generate serious heat. Soft fibre pods create a tiny gap between shirt and skin, and a metallic lining not only keeps warm air in, it reflects it right back at you. It sounds and looks a bit sci-fi, but it works, and this top is noticeably warmer than others of a similar weight and thickness. It’s also breathable, and has been treated with an antimicrobial substance. The liner is surprisingly comfortable, as the four-way stretch means you can move freely. It’s cut long and has thumb-holes. VERDICT 8/10