Back in the old days, long before I was born, salted crisps - or potato chips, for you yanks - came unsalted and had a little pouch of salt to manually shake on it. Of course, things are more efficient now, but Walker's still brought back the old 'Salt 'N' Shake' style a couple years ago. Dunno why, but if I had to guess, I'd say it's because the nostalgia crowd were getting salty.
Fat Base
Down Sprite Base
Face Bases