Northern Wheatears but where are they heading

really enjoyed these superb Wheatears yesterday with a minimum of 14 individuals all but one males; the pales bird is amongst these images that show a variety of birds but are they true Greenland Wheatears or are they heading for Iceland as seems to be the theory based on slightly paler underparts than Greenlands and the timing that fits well with arrivals in Iceland -- any thoughts / comments welcome