"The Green Roads of England"
by R. Hippisley Cox (first published 1914)
24 illustrations by W.W. Collins; 8 maps; and 87 plans. Much in there concerning Avebury and hillforts.
I found this little gem yesterday - a facsimile copy published by The Lost Library (ISBN 9781906621056).
Edward Thomas mentions this author in the front note of his book The Icknield Way - thanking him for his help and kindness.