If The North Face Warm Zip Neck is a modern take on baselayers, the Kailash is a more traditional variety.

It has a long, below-the-waist cut, thumb loops and it’s made from wool – 18 micron yak wool which Peak to Plateau claims to be warmer than merino.

Such fine wool has its advantages: it doesn’t itch or scratch – offset seams and flatlocked stitching help here, too – and it can trap more air in its fibres, increasing warmth.

I used the Kailash every day for three weeks – either to sleep in, for walks and beneath my other clothes – before finally throwing it in the wash. Though I wasn’t often over-exerting myself, this shows an impressive odour-resistance – a natural feature of yak wool.

The top is said to be slim cut, but I found it a bit loose on my frame.

I really appreciated sleeping in it on cold nights – it wasn’t restrictive and it kept me warm.

The thumb loops are a good feature, ensuring sleeves don’t ride up and the long cut means it can be worn beneath a harness or tucked in.

One drawback is there is not a female-specific model. The size medium I tested weighed 220g.

This is an expensive item, but its superb comfort, warmth and odour-resistance have made it my go-to baselayer.