I have been trying for this species and a  photo ever since I had access to the wood.  Yesterday I had set up a new hide, lower and nearer to the waters edge. I suspected that it was only going to be a matter of time befor the Green Woodpeckers came to drink while I was in the hide and this morning, after I had been sat for only a minute or two in it came! At first it landed a dozen or so feet away from the water but very quickly it hopped towards the edge where it proceeded to drink heartily for a minute or so.  More pictures later today when I have had a chance to sort through them.  Just to mention, this is my first 'proper" chance to photograph this specie and the first time I have been within photographic range so it's quite an event for me and "Wildlife In a Suburban Garden".  The bird is a female with a black "moustache" stipe. In the male of the species this is red edged with black.