My wife bought me an Inov-8 Mistlite jacket as an early birthday pressie.
http://www.peteblandsports.co.uk/products/inov-8-mistlite-jacket-210-aw12.htm?brand=1
It's very warm & seems to be waterproof, as I tried the sleeves in the new fountain in Wakefields BullRing.
It packs down to 'bugger all' & even had its own straps, so it stuffs into its own poekt turns into a bum-bag (with extra space too!)
My only gripe;
It's black!!, not a good colour, even with the reflective piping that it has
Why they didn't produce it in red/orange/yellow is beyond me.............