Shelter is the most overlooked thing. A lot of crises can be survived with the ability to get through a wet cold night in OK shape.

Much maligned though they may be, a space blanket can make a huge difference, and can genuinely be carried in a shirt pocket so it is always with you.

I keep a cheap disposable poncho and a space blanket in most of my coat pockets - I may not be going miles from civilisation, but if I break my leg walking the dog in the woods, I intend to be dry and warm until rescue turns up