At Bad Archaeology, a skeptical look at Alfred Watkins and the “discovery” of ley lines:
According to a later account, all this [discovery of a hidden web of straight lines in the English countryside] came to him “in a flash” on 21 June 1921 during a visit to Blackwardine; according to his son Allen, this happened while poring over a map. A variation on the ‘origin myth’ quoted by John Michell holds that the revelation happened whilst out riding in the hills near Bredwardine in 1920, observing the Herefordshire landscape he loved. It is unclear why there are two different versions of the story; Tom Williamson and Liz Bellamy note wryly in their excellent Ley Lines in Question (Tadworth: World’s Work, 1983) that John Michell’s version reflects how “ley hunters would like to think it happened”.
Speculations about “trackways” and astronomical alignments go back well into the nineteenth century, before even Watkins’ time.
A critique of the Wikipedia entry for ley lines is included.