Putative Mew Gull

Had this amongst c500 Common Gulls in my local roost on Friday (28th),
Subtly smaller than CG with slightly paler mantle, yellow/brown iris, broad white tertial crescent, very dense head streaking (for time of year) which was strongest on nape and extended strongly on to breast, small dark spot infront of eye and hint of ear covert smudge, primary tips seemed larger than CG. bright yellow legs (not photographed), the bill was all yellow and lacked the ‘z” across both mandibles, it was perhaps slightly longer billed than I would have ideally liked but Olsen states that there is overlap with CG.
I see plenty of ‘hooded’ CG’s but not quite like this….
Comments welcome….