In reply to Basemetal:
After a hypothermia "incident" with teams of youngsters which we train (story around what you think you have forgotten, but haven't, it's just that it's now in your mates rucksack in an identical dry bag to yours after a hurried early start in the dark...), we now give them a high energy pack. They are required to carry emergency food as well, but the "pack" is a huge calorie hit if they find they have scoffed everything. Contents, chocky, and hot chocy sachets, energy gels, and lots of kendal mintcake. They are encouraged to use the packs....even if it isn't a big emergency, and the mintcake is the first thing that gets eaten!