This quote given by David and attributed to Alexander Thom is precious.
‘As the investigation advanced it became evident that I was not dealing with monuments orientated for some ritualistic purpose but rather with the remnants of a scientific study of the Moon’s motion. When this is recognized it will be found that a great mass of material falls into place.’
Kenworthy, David. Stonehenge: Cracking the Megalithic Code.: Book Three: The Eclipse (Kindle Locations 102-106). Kindle Edition.