This turned out to be a good move as I stumbled across a juvenile Iceland Gull among about 80 large gulls on the river adjacent to the Wetland Centre. This was actually the first time I'd biked down here this winter and it was nice to find a new spot for loafing gulls at low tide - Chiswick has generally been poor for numbers of large gulls in the past month.
Initial views of the Iceland Gull, Fulham, 2 December 2016
After about half an hour the bird decided to fly off west upriver, over Hammersmith Bridge (thus in to my regular 'patch'!) before turning north and disappearing off over the West London skyline. It turns out that this is the same bird seen by Pete Alfrey at Beddington on 24 November and then by Dave Harris in the Island Barn Reservoir roost on 28th - not that that's surprising, given that there are so few Iceland Gulls in the country at present.
A white-winged gull with Hammersmith Bridge in the background - the stuff of dreams