One jacket for a Welsh winter and a Turkish summer. We each own one and have not needed anything else for two years.

The vanlife packing constraint is real. Everything you own must fit into a relatively small living space and still cover every climate you are likely to encounter. A layering system that works from Brecon in November to Bodrum in October requires thought. The Rab Xenair Alpine Light is the piece that makes our system work.

The Xenair synthetic insulation performs when damp in a way that down does not — critical for the British uplands. It packs to the size of a large grapefruit, weighs 230 grams, and provides genuine warmth as a mid-layer under a shell or as a light outer in cool dry conditions. In Turkey in October it is cool enough in the evenings to want it; in Wales in November it is the layer you reach for every morning before the van warms up. We have had ours for twenty-six months and the insulation has not degraded noticeably.