Adult Iceland Gull / Larus glaucoides, Biezelingsche Ham (The Netherlands) on 15 February 2012
Interesting plumage to ageing, but I guess it's a 4th winter / 5cy. In most respect it looks like a full adult, there's only some pale brown wash on the upper-wing coverts and two dark bars at the undertail-coverts. The underwing-coverts are complete white and unmarked. Note the black marks of oil at p9 & p10 in the left wing.
From: Ies Meulmeester, Wednesday 15 February 2012, 20:41