Great Black-backed Gull (Larus marinus)
A big beast and, like its large congeners, omnivorous. This one was pictured on Ireland's Eye, a small uninhabited island of the coast of Dublin, where they breed. Not too be tangled with, this one took off after a pair of day-trippers who wandered too close to the nesting area. I have some photos of this but cannot post private pics in Comments anymore it seems.