Now, when \i first saw this bird I immediately thought it was a herring gull, but on closer inspection it looks a little strange, the overall appearance seems a little wrong for herring, The white mirrors in the wing are not very well defined either. Basically it just does not look right.
I dont know why but i was sort of thinking maybe caspian? I may be wrong but my mind needs to rest with this one! Appologies for the soft photo,this was late evening in scarborough, and i was cold!