Eddis, Attolia, Sounis

From the Fosseway westward to Isca Dumnoniorum the road was simply a British trackway, broadened and roughly metalled, strengthened by corduroys of logs in the softest places, but otherwise unchanged from its old estate, as it wound among the hills, thrusting further and further into the wilderness.

This should be easy, especially since MWT references this book in 'The Thief.' The author was a brilliant writer, and if you haven't read any of her books you should run, not walk, to your nearest bookshop or library or second-hand shop and buy her books!