"Walls" is an archaic term which used to be used to be used to describe vertical sections of "wall" along the length of a ridge tent, making much more of the width usable. My first (green, waxed canvas) tent was 6x4x3 with approx. 10" "walls", making it quite useable for two teenage boysfor up to a weeks camping. because of financial constraints, I had to choose between having a sewn in ground sheet, or a fly sheet. Given Welsh and Lake district weather, I chose the fly sheet. It made for a nice extended porch when deployed in fine weather in front of the tent. Wall-less tents are called "pup" tents over here. Hope you enjoy your find, but you will have to crawl to get in and out, and probably have to go in forwards and come out backwards, because there's no room to turn around
Update - seems there is still a whole genre of canvas tents over here called "Wall tents" - much bigger and more expensive than I had in mind. Examples at:
http://www.springbar.com/shop/products.php?cat=32