It isn't too clear either way and comparison with
http://www.themodernantiquarian.com/post/25616
might lead you to say the stones were the front stones.
The suggestion that they were probably the back stones picks up a Frances Lynch comment about a "rather poor sketch" by Stukeley which shows two triangular stones to the E of the present remains possibly marking the original entrance. (Megalithic Enquiries p129)