Now you see it, now you don't..

I'm am not quite sure what this bird is. I thought perhaps a sandpiper of some sort but despite consulting all the books and websites, I could not nail it. I photographed it on the beach this morning at Barns Ness. I initially spotted among the seaweed and hoped I had mananged to focus accurately on it and then it proceeded us on the path off the beach so I took a second shot. It is amazingly well camouflaged in the seaweed even though I have made it easier to see by selective sharpening it.

Any help in idebtification would be gratefully received.