REMAINS OF A MOTTE AND BAILEY castle.In the image,the defensive ditch for the bailey can be seen about 2/3rds of the way up the rhs of the image,traversing to about halfway across the picture.This view is from the adjacent churchyard.
see http://www.ecastles.co.uk/stockbury.html
see http://homepage.mac.com/philipdavis/English%20sites/1664.html