The NW (or North-Western if you prefer) is a generic prefix (though not used as such by e.g. UK400 club), hence my abbreviation here (and in the Birdguides report). It conflates rostrata from Greenland (and adjacent areas of the northern Canada) and islandica (obviously from Iceland). The former are generally not hard to identify (at least in fresh plumage) being essentially like a massive Lesser Redpoll; very big, brown, and streaky. Though not recognised as a valid taxon by all authorities Icelandic birds are another story entirely being very variable; some resemble rostrata, some resemble flammea (Mealy), and some (very closely) resemble exilipes (Coues' Arctic Redpoll), hence the request for specific details.