No problem, gulls are a nightmare! But fun 🤪

..to look, which is what this is.

First photo does look quite Caspian ish (snouty, bit of a shawl) but in second photo you can see tertials are second gen which, as you say, makes it a 2cy bird. The plumage is not advanced, as Liam has said the GCs look messy, the legs short, etc. in fact looks exactly as you’d expect a 2cy Herring

Another vote for 2CY, second and third gen tertials - as Tom says with the large pale irregular tips with what looks like two new grey tertials too.

Flounced Rustic I think

Yes, seem pretty regular in Hove too. Fairly recent UK colonist

imo ESU is a more useful measure which the US uses (at least in theory).

I think this is an artefact of the twisted wing making it look white winged. You can see the mirrors on both wings if you zoom in 👍

Thanks Daryll, that would be great