Here's an article from the Daily Mail UK on the discovery of another Stonehenge-type calendar in Southwestern England.
All of the stones were intentionally toppled around 2,000 B.C. and the site may have been built at the beginning of the Early Bronze Age. It would seem that regardless of who built it or who destroyed it, that it's lifespan covered most of the time in which Beakers were active.
Southwest Britain became a central player in the exploitation of metal deposits in the Early Bronze Age. The moors may have made an ideal place for surface mining. You'll notice that the current arc forms an East-West orientation.
Just looking casually at the map, Shoveldon could be oriented toward the Equinox, whereas Whitmoor and Sittaford could be oriented toward the Solstices. Those in between may be Cross Quarters (such as Halloween, Lughnasadh, etc.) Of course this assumes a degree point to which all are vectored and again that there is not yet a full circle or other shape to be found.
You can that someone tipped all the stones over, deliberately in the same direction, around 2,000 B.C.
A very convenient time frame in British prehistory. Maybe someone was pissed off, or maybe "alcohol was a factor". Another possibility is that the religious views were changing a bit at this time.