Here’s an example of four monuments all roughly the same period and type and certainly prehistoric (two chambered cairns ((one of which has rc dates of bone 3650 to 3380 Cal BC)) , a tumulus with a cist ((including RC dates 3660 to 3380 cal BC)) and a cairn with a cist )with similar distances to the three main Maen Llia examples . With no other monuments within their greater “triangle “ .
See : http://tinyurl.com/ljgn5lp
“Ossians” mound =1 ,The westernmost chambered cairn=2 , the cairn =3 and the easternmost chambered cairn i.e. Torrylinn =4 . Among the four monuments are three separate groups of equidistant measurements .
1-2=276m , 2-3 =276 m, 1-4=615m , 2-4=615 m and 1-4=334m , 3-4=331m .
This is one pair of equidistant measures more than at Maen Llia ,with one less monument , all the monuments are roughly contemporaneous and certainly prehistoric .
N.b. this is mentioned for demonstration purposes only and there is absolutely no suggestion that it is a newly discovered example of the siting of monuments by measure .