I found this pic of saddle stones and support lintels for a hayrick at nearby Chatsworth (near the kids play area and pet zoo) so say 3 miles away?
Bang goes the hayrick theory as the stone shapes are nothing alike and they aren't going to change in design over such a short distance from each other
http://www.flickr.com/photos/79289196@N05/8637437216/in/photostream