Caspian Gull?

Caspian Gull?, Cottenham, Long Drove, 26th November 2008, © Dick Newell
The plumage of this bird looks adult, except for some black on the primary coverts. The wing-tip pattern was near classic "adult" Caspian Gull, with a small amount of black on the white tip of P10. With no red in the bill it is probably a 3CY. However, its legs were rather thick and rather pink and the bill-shape looks slightly off. It was carrying a green ring, 8P15, on its right leg, so it was ringed somewhere in Poland. It will be interesting to see what it was ringed as (RGN).