Thanks Carl.
On the Portal's sitepage for La Haye D'Ectot I included a link to a "dance studio" webpage which used to have pictures including the Allee Couverte, but which are no longer there (although it is still mentioned). In the past I spent some time looking for this, and narrowing it down, but never actually finding it. Maybe Carl now has better information, but from memory (very full and fading) the picture does not look like what I remember seeing on the website.
Please bear in mind that the position data on our sitepage is a rating 2, (to nearest village and I believe placed near the Marie), so you will find nothing at that position.
I assume when you talk of the OS map (do they do maps of France?) you mean the local ign map, versions of which are available on the ign geoportail site, linked to directly from our sitepage icons near the top.
Maybe I need to have another look myself next time I am out that way with an afternoon to spare.
Something is not right. This message is just to keep things from messing up down the road