Seconding Kevin M's and Alvaro's comments, I would agree that the Outer Hebrides bird is a clear example of a juvenile WESTERN SANDPIPER. Here on the eastern Great Lakes it would certainly stand out based on plumage alone, regardless of bill/size shape.
As an example there is an excellent comparison photo of juveniles of these two species standing next to each other on the Point Reyes Bird Observatory "Los Farallones" blog here (scroll down to last photo in entry):
http://losfarallones.blogspot.com/2012/09/another-fogged-in-day-on-farallones.html
Jim Pawlicki, Buffalo, NY