As previously mentioned by Hattie, archaeo's (from the University of Reading Archaeology Field School) had been poking around underneath Silchester. They've moved on, and this year's Field School is at Marden Henge.
Coincidentally, on the same weekend, Chateau Boreades is playing host to folks working on that, and an International Documentary Film Crew(!) - Hattie will reveal all regarding the latter in due course (shhh, TME teaser).
Meanwhile the folks fiddling in the middle of Marden are getting excited because they've found a Neolithic building, with a pig's jaw. I forget where I read it, but IIRC it was said that the interior of Marden was originally covered with a smooth flat layer of clay. The trad. archaeos trotted out the stock "ritual significance" phrases with no insight into what it was meant to be used for.
Our insight was that you bother lining something with clay if you want to make it waterproof. From there, we might ponder on the significance for astronomic observations of having a flat pool of water that reflected the sky above.