A wingflap revealed the expected pure white underwing......
Obviously identification using plumage detail is next to useless with a gull like this. Its' all about size and structure. Size and jizz seemed to exclude Herring Gull. The bill is the only bare part coming into play and the length / shape to me suggests this is a leucistic Lesser Black-backed Gull. Compare with the Herring and Lesser Black-backed gulls below.....
This gull is doing the rounds within the Midlands and Steve Whitehouse confirmed it appears to be the same bird seen at Wildmoor tip (Worcestershire) a few weeks ago. The power of twitter kicked in with Wayne Dutton noting that a gull fitting with this one was present at Bartley Reservoir (West Midlands) a week ago followed by Throckmorton tip (Worcs) over the weekend.....