Yellow-legged Gull

From wikipedia:
Adults are similar to Herring Gulls but have yellow legs. They have a grey back, slightly darker than Herring Gulls but lighter than Lesser Black-backed Gulls. They are much whiter-headed in autumn, and have more extensively black wing tips with few white spots, just as Lesser Black-backed. They have a red spot on the bill as adults, like the entire complex. There is a red ring around the eye like in the Lesser Black-backed Gull but unlike in the Herring Gull which has a dark yellow ring.

First-year birds have a paler head, rump and underparts than those of the Herring Gull. They have a dark bill and eyes, pinkish grey legs, dark flight feathers and a well-defined black band on the tail. They become lighter un the underparts and lose the upperpart patt... read moreern subsequently. By their second winter, birds are essentially feathered like adults, save for the patterned feathers remaining on the wing coverts. However, their billtips are black, their eyes still dark, and the legs are a light yellow flesh colour.

The call is a loud laugh which is deeper and more nasal than the call of the Herring Gull.