OA makes no mention of Fred Hoyle's 'three hours with a calculator' to check Hawkins figures (and being generally unimpressed). Also nothing about the Thoms (Alexander and Archie) who surveyed many other stone circles, or perhaps a passing reference to John North's chunky book on Stonehenge itself. Latterly Euan MacKie was working out how exactly you could test an hypothesis about ancient observers marking a celestial alignment of some type anywhere in the latitudes of Britain. A multi-route rabbit hole if you are in need of diversion.