Herring, Yellow-legged and Lesser Black-backed Gulls of various ages drifting downstream on the ebbing tide.
The first good bird of the day was a second-summer Mediterranean Gull in amongst the fray of birds on the tip. An hour and a half later I found this individual, either the same bird or a second one, on the foreshore. Note in the shot below how much more extensive the black is on the spread outer primaries than appears to be the case when perched, and also the extent of primary moult (P1 and P2 are regrowing and it has just dropped P3). This is surely the most attractive Med plumage.