Black-backed Gulls (1 Viewer)

Can you please guide me with these two ... I am pretty sure the single image with the dark back is a LESSER BBG due to the yellow legs but the "1st winter" one I think may well be a GREATER BBG (red legs) but I am not 100% sure it is not a HERRING gull or even a CASPIAN gull (one has been seen in the exact location yesterday) .............. please assist.

1st winter/2cy Herring Gull - note pale inner primaries, & adult LBBG

A GBBG would have a lot less streaking on the head, too.