Yellow Legged Gull

Last night about 7.10,I noticed a group of 14 LBBGull heading west,as I was watching/scoping a kestrel at the time I decided to have a closer look at the gulls immediately one stood out to be a grey backed gull, similar in shape to the LBBGull's,as it banked sideways the yellow legs could be seen.Its well worth looking at all groups of LBBGulls at this time of year for a Yellow Legged.!!!!Good luck