Under the personal guidance of the late Professor Alexander Thom studies of the archaeoastronomical potentials in Mid Wales prehistoric sites were begun over two decades ago.
The resulting photographic data with computer surveys give strong support to Thom's theories on the existence of the Megalithic Calendar and a Lunar Standstill program in prehistoric Britain circa 1800 BC
Many photographs and videos have been taken from stone circles and standing stones on days corresponding to dates in the Megalithic Calendar and Lunar Standstill periods. When the Sun or Moon crosses the horizon other megalithic monuments, of similar antiquity, are clearly silhouetted on, or very near, the disc.
Digital surveys of these images, employing time-rewind, demonstrate that sophisticated systems of positional horizon astronomy were practiced in Scotland, Cumbria and Wales circa 2000 to 1600 B.C.