Juvenile gulls are starting to appear at Shawell A5 Lagoons. Young Black-headed and Lesser Black-backed Gulls are the commonest. At least one juvenile Yellow-legged Gull has moved north already. Yellow-legged Gulls are usually commonest at the end of July in Leicestershire, so it is not surprising a few juveniles have moved north with the older gulls.
They are not the best images of the juvenile, as they are just screen grabs from a short video, but the features all show up: whitish head with dark mask around the eyes, chunky all black bill, dark tertials with thin pale edges, the top greater coverts stand out as they are darker and not so heavily patterned as the lower ones and finally it's much bulkier than the juvenile Lesser black-backed Gulls that were also present.