Looking very similar, though much smaller, a dainty Wood Sandpiper has returned from the breeding grounds in Scandinavia (or possibly Scotland even), a slender bird with spangled breeding plumage still evident. It's strong supercilium gives a slightly intense look to it as it pokes at the surface for small flies.
Two green sandpipers loafed on the muddy shore, before venturing out onto the water to feed. superficially like the Wood Sand, the Green lacks the obvious supercilium, and its spangling is not as bold. The dark underwings and broad tail bars are a real giveaway.