I had these gulls at a stream outflow into the Gulf of St. Lawrence, on Cap d'Éspoir beach, Gaspé, Peninsula, Québec, Canada on 19 Sep 2011.
Top panel shows what I think is a first year (chick in 2011) Herring Gull, and to the right, the individual in question. Bottom panel shows the individual in question and to the right a young Great Black-backed Gull. Based on the small size of the individual in question, and the very light, "black-back-like" head, I am thinking maybe Lesser Black-backed. However, I can see some grey coming into the mantle of the bird which, with the light head may indicate a second summer (chick in 2010), small (female?) Herring Gull.
The bird does not appear to be a Lesser Black-backed to me. The bill if the first thing that jumps out. LBBG normally has a fairly parallel sided bill with a small bulge at the bottom near the tip (the gonys or gonydeal angle). Your bird seem to swell on the upper mandible and have a pretty strong gonys. The bill also looks strongly bicolored with a fairly pink base. I'm used to LBBG having a less neat bill pattern change from black to adult, and usually with a pale tip.
You already mentioned the new feathers looking too pale, and I agree. I also think there is way too much pale edging on the old feathers for LBBG. Finally, I think the head looks kind of long and flat, perfect for Herring but it seems a bit too exaggerated for LBBG to me.
I think this bird is a Herring Gull, and I agree with you on the age.
I agree with Paul on this bird. The pale gray feathers coming in on the back, mostly clean white head, yellow eye, and distinctly bicolored bill all point to a 2nd cycle Herring Gull. Though not in profile, both images suggest that the bird is fairly long-legged and short-winged. Lesser Black-backeds usually strike me as long-winged and comparatively short-legged. There is no plumage of Lesser Black-backed Gull that would show pale gray mantle feathers like this bird. Additionally, note the strong gonydeal angle of this bird, which matches that of the 1st cycle Herring Gull in the first photo. Young Lesser Black-backed Gulls normally have a thinner looking bill than young Herring Gulls, with minimal expansion at the gonys.