It wouldn't harm to do more prospecting around the wider site. Possible avenues include - Rock Art on the faces of Devil's Arrows? (I'll volunteer Hob to take the X-Ray photos), where in the bridge is the fourth Arrow?, and I remember a sequence of standing stones, shown on a quite old map, that appeared to be an arc of a very large circle (it wouldn't harm to walk out the circle and see if there's anything to be found). The wider site certainly stretches from the henges, at least, to the Devil's Arrows, in that direction. This is too large a size for planners and administrators to comprehend.