Large White Bird is is it A Great White Heron or a GreatWhi te, White Egret

Is this a Great White Heron or Egret

This bird is a very very large and is to be found on the 'lakes' just up the road from Dungeness RSPB going towards Greaststone.  I managed several shots but was too far away and every time I tried to move in closer, the rotter stalked into the reeds, I am pretty sure it has black legs, but not a good enough shot to prove it.