I have already raved about the magnificent "Campers Handbook" by Thomas Hiram Holding, it is an amazing time capsule of outdoor knowledge. Written in 1908, Hiram was a pioneer of outdoor recreation. While the main focus of the book is on boat and bike travel there is a section on what he calls "pedestrian camping."
His kit for two people is as follow.
A base weight of under 10lbs puts this list firmly in the ultralight category.