What am I?

I've pondered over this for quite a while and the best I can come up with is possibly Grey Plover or Sanderling.........but either way I think it was lost as it was completely alone and those sort of birds are usually found on the coast or at estuaries.....we couldn't be further from either if we tried. Anyway, I've never seen one before, what ever it is.....although I bet I know a man who knows.......are you there Daver?
It didn't seem bothered by me or the camera and let me get quite close to take lots of photos ( I've added an extra showing some different angles and with a swan for size comparison).
I would love to know exactly what it is if anyone can identify it  :-))

UPDATE - My thanks to Daver64 who has now identified it as a Knot :-)