1st winter white-winged gull from the barrage at 09:00 for 15-20 minutes mostly well offshore but finally came in close enough to get some very poor photos. Size-wise appeared smaller than nearby Herring Gull and the profile when sat on the sea suggests Iceland. Primaries appeared paler than rest of wings, despite the appearance here. Any thoughts? Also adult Med Gull
Glamorgan Bird Club 
Certainly a glaucoides imo and do I see some slightly darker outer primaries – in which case could be a pale kumlieni?
Unfortunately those are the best pics! May have been a hint of dark in the primaries but most of the time whenever it was wheeling about and showing its upperside the primaries looked markedly paler than the rest of the body – probably will never know as it was last seen sat on the sea drifting down channel on the falling tide 😦
Looking at this again there’s little doubt in my mind this a Kumlien’s.