I picked this thing up off Sanblister Beach (in front of the house), the first thing noticed was a virtually all dark tail and generally dark plumage - pointing towards a 'Smicker', however, the bird is clearly too small and on closer inspection looks sod all like a 'Smicker'. It does however superficially resemble a juv/1st year Lesser Black-backed (mega rare on Shetland in winter), but this doesn't seem to fit either, as the pale 'window' at the base of the primaries should eliminate LBBG, but if it's not a LBBG it's probably got some in it somewhere.
Again another dark looking bird but definitely not a 'Smicker', presumably it's a dark 'argentatus' with a lot of juvenile plumage still retained. Some photos of a similar looking bird (though a second winter) in Denmark - photos here
A pretty mad looking adult type Herring Gull, but the bird is in a late moult on the primaries and has an looking, parallel sided bill. the mantle shade and numerous white mirrors suggest 'Argentatus' (which it almost certainly is), but that bill, moult timing and fainter head streaking suggest maybe there's another influence in the genes of this bird - see here- a bold call, but Gulls do have a habit of interbreeding with anything that vaguely resembles themselves !
A bit of a doddle really - a big, monsterous, adult 'Argentatus', though it may not be a full adult as there does seem to be some brown flecking still in the wings.