After a good hour or so, finally located the Sandpiper as it flew in from upstream. I suspect this bird is Common but would love to be proved wrong as I haven't had much experience with winter Common or Spotted Sands. The thing that does worry me is that the legs aren't as yellow as I'd like them to be for Spotted and I also heard it call just like a Common so an over-wintering Common Sand seems likely this time! From the pics it does seem to have a slightly shorter tail projection than what a normal common would have in my opinion but whether that is a 'winter' thing, I'm not sure.
Video is better for seeing over all shape of bird and character