Here are a few pics from local birders Bryan Formstone and Hugh Linn.
Firstly of the first winter Caspian gull.
Next a couple of the adult bird, which is almost certainly a yellow legged. However it had a small dark eye and primary 10 was very white. However overall shape and mantle colour would suggest yellow leg. This was a beast of a gull, huge bird.
Without a wing tip shot I guess then we may not know for certain but there maybe others who can tell without.
Great to see a lot of north Wales birders chasing a rarity on our patch for a change!!