Picked up this interesting looking Juv Gull at Seaton Marshes this evening at 8pm. Intial thoughts rang bells on juv YLG but looked different from some other YLGulls I've seen in the past. Long thin black bill, dark black well defined tail band, bright white rump with little streaking, pale white face with dark eye mask, black upper edge to secondaries, slightly larger size than Herring Gull nearby (see images) and head shape looked elongated giving slender head shape like Caspian Gull. Plumage on wings quite grey. Thoughts and comments welcome please. Pics also posted on Twitter.