Years ago I picked up the book "SAS Survival Handbook" written by John "Lofty" Wiseman in an airport. His resume on Wiki is pretty impressive, youngest person to ever pass SAS selection (at 18), and eventually became the SM. Hopefully it's all true.
In his book he talks about having a small survival kit that is pocket-sized (one of those plastic cigarette cases for people who roll their own smokes) so that it never leaves your pocket. In this kit he lists a few things, but of course some of them you would already have on you anyway (such as a compass), this is a guideline, not a bible.
Matches - dip head of match in wax to waterproof it, break in half to save space.
Candle - Tallow wax is fat and is edible, but doesn't keep well in warmer climates. Paraffin wax keeps better but is not edible.
Flint
Magnifying glass
Needles wrapped in thread
Fish hooks wrapped in line
Compass
Beta Light - only the size of a small coin but ideal for reading a map at night and a useful fishing lure - expensive but everlasting.
Snare wire
Flexible saw
Water sterilizing tablets
Condom - good for about 1 litre of water
Fill any extra space with gauze for tinder/first aid and to prevent rattling.
Then he says having a survival pouch which is actually part of your kit, as opposed to being in your pocket at all times. It's got all kinds of stuff in it, but it's not written in a military context. Most of the stuff in the survival pouch you would have in your kit (such as mess tin, fuel tablets, flashlight, more matches / bic lighter, etc).
