Juvenile Yellow-legged Gulls

I had five juvenile Yellow-legged Gulls in the Peterborough area today (four at Dogsthorpe, one at Tanholt), making it the most common age-class of the day. I guess more and more will appear as the month wears on. The only other michs seen today were the Caspian-like 1st-summer (from last week) again at Dogsthorpe, and an adult at Tanholt.
A couple of juveniles are illustrated in the images below: