So do I , I don't buy the Thom precision stuff . It just means that things are a bit fuzzier and it's more difficult to show intention . As far as Long Meg goes it's very difficult to find the centre which is usually considered where to start for an "alignment " ,but anywhere give a few metres and look through the portal or Long Meg , which is nearly two degrees difference over 80 metres so quite a wide horizon to pick from , and the solstice sun will set in that general direction . I find that acceptable but difficult to prove and certainly not "precisely " aligned .