Hi, saw this gull at Staines Reservoirs. There was a record the previous day of Caspian Gull which is why I'm asking.
Hi Rishaan, google lens agrees Caspian Gull ! Personally I don't know how reliable this answer is but it will bump up your post so that others can see it!
it doesnt look a classic CG to me- but the angle of the photo isnt helpful :(
I agree its got nicely edged tertials but its not snouty and the bill is a bit short IMHO
Have you got any more photos? S
First image is the same bird, only other photo. Second image is another bird. The second image I considered a Herring, but it has a more appropriate bill size for Caspian.