Are there any signs of a Great Enclosure enclosing the old manor ? Patches of hedge often survive which show as characteristic sweeps on the Victorian 6" OS.

The limpet shape of the hill suggests prehistoric origin but folk memories of middens - tipping sites for refuse - are very long. A 25" town hall map would yield the dimensions of Silbaby quite simply - a rough approximation could be made from the present 6" survey.

One direction of ultimate proof lies on the azimuth defined by Thom as between the Sanctuary and Silbury Hill. From the Sanctuary *now* (09:24) the moon will be seen setting behind Silbury. (In Newcastle it sank into a bank of cloud half an hour since). Tomorrow, perhaps an hour later, the alignment will be closer. The weather forecast is for a frosty night followed by a bright morning. I don't think this alignment has been 'tested' for two or three thousand years. (Thom & Thom just surveyed the alignments and didn't actually test any).