Despite the dark eye on the right hand individual, I think these are both Herring gulls. This is my 12,000 record on iNaturalist.
Absolutely huge! Bigger than the black-headed gulls and avocets on the same sandbank. Reported all day on 'Rare Bird Alert'. See my journal entry: https://www.inaturalist.org/journal/heliastes21/95956-a-strange-tern-up-for-the-books
Three CONI day roosting on fenceposts near riparian area.