“This rock is in the adjoining field and the five marks are each (coincidentally) two megalithic inches long. The pattern is too irregular to have been made by a modern stone cutter and 'points' toward a large mound, named Priests Crown, a mile or so across the Barrow Bridge Brook valley.”
http://www.themodernantiquarian.com/post/50973
Sorry to offer an alternative view, but the marks look regular, the size could have something to do with the same chisel being used, and the reason for their orientation could have something to do with it being the stones longest axis, thus less feathering! It may not have been modern man that created these marks, I understand that in some areas pretty much the same methods were used from Roman though to Victorian times.
