In reply to belfast_phil:
For the walk in:
Paramo trousers
t-shirt or longsleeved thermal top.
25ml bottle of water in trouser pocket for constant hydration.
packet of winegums in same pocket.
ditto with some lip salve.
thin fleece gloves and thin fleece balaclava in other trouser pocket
in rucksack:
spare hat
shell gloves to go over fleece gloves
(possibly mitts if it is cold)
Pertex windshirt.
fleece top (not a heavy one)
very lightweight waterproof jacket
crampons and axe(s) as appropriate for the planned route
rope and rack and harness as approppriate
belay jacket (sometimes)
water
food
foil bivvy bag
Bothy Bag (aka emergency shelter)
basic first aid kit (ibuprofen and plasters)
map and compass
whistle
head torch (LED)
paper tissues (I have a dodgy gut and never know...)
car keys
mobile phone
camera
Unfortunately, I have had to use all of these at one point or another. Fortunately, not always on me.