The two tall stones in the foreground are the portals as far as I'm aware, they are (by far) the tallest and the rest are graded down to the axial, and Burl mentions that the low bank surrounding the circle has a gap here too. If Burl is correct then we have a standard axial stone circle with the axis through the portals over the axial stone indicating mid-winter. Pretty much a standard of the type (like Drombeg?)