Side flash wouldn't do a lot of good with this one because of the shape of the stone. What you need is a good setting sun at the right time of year, which is what I was fortunate enough to have when I managed to find it - http://www.themodernantiquarian.com/post/20762

My visit here was prior to my logging the 10 figure references. However, the grid ref I give is 100m more accurate than the official one in the Archaeological Inventory. As I could walk straight back to it I should get up there again and record it so that Ken and test his GPS out :-)