[CT Birds] lesser BB Gull question

[Carrier Graphics]

Today at the Bristol Reservoir, I had a strange gull. 
I believe it to be a 2nd winter Lesser BB Gull, but need help.

It was in with 1 adult Herring gull, winter plumb typical streaked head and light grey back, pinkish legs and yellow bill.
This other bird was with it, and was about the same size, but it caught my attention from being darker, looking much like Sibly's 2nd winter Lesser in his book. 
This darker bird had pale legs tinged to yellow,(not flesh or pink) a bit darker grey back with wing feathers mostly DARK brown with some grey in them. ( I believe all Herring plumbages do not have this dark wing feathering, yes?)The bill as best I could see was mostly dark, but light at base. The head was also streaked and dark, unlike the Herring whoes winter stripping was noticably lighter.

Just on the neighboring rock were 3 Greater BB Gulls for size comparison. I am fairly confident it was a Lesser, but I think some Herrings might have yellowish legs? But the dark wings were what I noticed most, and believe this bird could not have been a Herring - - yes?

Not being an expert Immature gull birder, I would appreciate any help with this ID. Thank you...

Paul Carrier