Packable rain protection from… California?
Don’t let the California address mislead – based in damp San Francisco, Mission Workshop (Acre Supply if you’re dirty)  knows a thing or two about waterproofing. Not convinced? Their lightweight/packable waterproof – the Orion – is cut, sewn, and seam-sealed in Vancouver, the Wales of the (North American) West Coast.
With a relaxed cycling cut, the Polartec NeoShell (96g/m2, for those keeping track at home) piece should be well-suited to both mountain and urban adventures.  The peaked hood is removable, pits are zip-able, and pockets are… pocketable?  That NeoShell fabric is among the more breathable waterproof/breathable fabrics on the market – and Richard has found it to be sturdy to boot.
Top-shelf fabrics, Canadian craftsmanship, and an aversion to compromise don’t come at all cheap – £375 in this case. That works out to roughly one pound per gram – but if aspirations demand and means allow…