I had this wader on Holden Wood today morning which in structure resembled a Wood Sandpiper but looks closer to a Green Sandpiper.

It looks elegant, the neck seems longer and it almost has a good supercilium which seems to indicate Wood Sandpiper

However, the bird seems to be darker and the upper and under parts contrast.  The border appears quite clear cut.   The supercilium doesn't extend beyond the eye.

Appreciated that moult and the conditions will distort colouring.

EDIT Green Sandpiper it is 

Opinions welcome