dunno. Is there a chronological 'advance' in the designs throughout the country? The features ought to be datable by pottery in them, whether the postholes overlap other features 'n' stuff.
They are a neolithic idea though are they not. Stone circles are much more your bronze age thing. So are you saying that the henges (once used for mundane things like animals and football) were later taken over and used for 'ritual' and vv?