Ironically I think the very archive that would assist is actually in Swindon.
http://www.english-heritage.org.uk/professional/archives-and-collections/nmr/archives/ So of course this will already have been checked, before going public in a newspaper. Well probably. Not.
Secret knowledge, it's great isn't it. I know it's 3000 years old. I know it shows an owl and a spaceman. I know it was looked after by pagans for hundreds of years. No I'm afraid I can't show you the photos, they don't come out well in a newspaper apparently. Or now (as we're told above) we're not allowed to see them until the work's published (in which prestigious peer-reviewed journal I do wonder). You'll just have to believe me. Oh and if you're interested I've got a great second hand car you might like.
And the all that is associated with the Ridgeway in that area, including Wayland's Smithy. Just wish the image looked more credible instead something resembling an adolescent fantasy.