I did Wall Common over high tide today, and a good selection included a fresh juv Med Gull, 9 Whimbrel, quite a lot of Dunlin, and about a dozen or so large gulls loafing on the beach. In amongst them was a sub-adult bird which immediately set the internal alarm bells ringing: darker mantle than the adult Herring it was stood next to, slim, long-legged, dull slim bill, dark eye. All looked good for a Caspo.

Then at 1pm the beach was suddenly invaded by a collection of people (including boisterous kids) and 9 dogs! Everything flushed of course, and the large gulls all seemed to head towards Steart Point.

Reading up this afternoon I am happy that my suspicions were right, and that it was a Caspian Gull, probably 3rd summer (4th calendar year), though I'd have loved to get more detail and possibly even photos. Worth keeping an eye out for if in the area tomorrow.