Think you are probably right..
http://farm1.static.flickr.com/131/368118599_890493d4b1_o.jpg which is a Stukeley aerial view, the circles are interpreted in a peculiar manner ;) but there again we should'nt be too hard on him, he did a good job considering he only had pencil and paper ....
there's also this map in the Underhill Archives;
http://web.arch.ox.ac.uk/archives/underhill/viewarchiveslide.php?imageID=26&albumID=1