I recently spoke to a guy who does mountain marathons like LAMM and Karrimor (as was).
Because you can't run absolutely all the time (too busy looking where your feet are going) and the fact that they are out for about 7 hours, bit like a 'not quite as fast as the others' marathon runner. He said he takes:- Kendal Mint cake, Eccles cakes, Fig rolls, jelly babies. He also does take gels, because the race organisers on these events insist that runners ahve emergency provisions, but almost never uses them.