Baltic Gull?

Possible Baltic Gull, Milton, 23rd December 2006, © Dick Newell
Had a ringed Baltic Gull not turned up in Holland recently (here and here), I would have dismissed this as a possibility. Although the plumage tones are not as distinctive as the Dutch bird, this bird was small, barely larger than a Common Gull, and with enormously long wings, notably longer than the Dutch bird. As with the Dutch bird, it still has juvenile scapulars, though it appears to have moulted the inner greater coverts. Chris Gibbins suggests that the ratio of primary extension beyond the tail to the distance from the centre of the "knee" to the ground is a possible discriminant. The largest intermedius that he measured had a ratio of 1.2, but his sample was small (10 birds). This bird has a ratio of over 1.3. A further supportive feature is in the 3rd picture where it seems to have a very pale lining to the inner wing, this is a feature of some juvenile Baltic Gulls. However, the overall muddy tones perhaps do not support an identification of Baltic Gull. [It is quite possible that the Common Gull is heinii: it is dark, largish, has a small-looking bill and has a hanging wing.]