I've just been writing about Boundary Stones and the tradition was to blow a horn and to beat both the stone and young lads with sticks on an annual tour of the boundaries. The best known blowing stone is here - http://www.berkshirehistory.com/archaeology/blowing_stone.html - and the sound from it would have surpassed any contemporary ring tone.
In the photographs the bluestone looks blue - it seems the same material (in the picture) as that obtained from the S Wales mountains. (Glacial drift theories must always be vague). And the menhir - reset or originally placed - is set to topple. If its footings were dry it would be ok, but they're not. I wonder if the northernmost moonrise can be seen on the horizon from there ?