The ring read X574, which quickly confirmed it as the same bird seen by Jamie Partridge over at Thames Barrier Park the previous day. Ironically, while watching X574, I received a message from Jamie to say he'd got the first-winter I saw in Fulham back on 19 September! A fair swap, I'd say.
Although some of the 'Casps' from this colony can look pretty questionable, it's fair to say that X574 looks fine for a pure bird. A big and aggressive beast (presumably a male), it was very vocal and gave a full range of classic cachinnans calls, which made it very easy to pick out as it swooped in to the melee attracted to my wholemeal bread offerings.
So, as mentioned previously, my fourth Casp of the season here. Though I'm already well behind Rich, Dante and Jamie's nine (as of 23/10) in the Thames Barrier/Greenwich area, I can't ever really expect to keep up with this East London hotspot given the greater number of gulls moving up and down the Thames Estuary. However, I'd be very happy if I make it in to double figures by spring (last winter I had a total of four, although at least a couple of extras were recorded by other birders).
Also on show on Sunday were at least five Yellow-legged Gulls, a very decent tally for October given that there were 'only' about 150 large gulls present (100-200 individuals is about average here at weekends). Monday's session was nowhere near as impressive - reduced numbers included 'just' three Yellow-legged Gulls and at least one Lesser Black-backed x Herring hybrid.
1cy Yellow-legged Gulls, Fulham, 22 October 2017 - the top bird has a distinctive bill and should be easy to track around London this winter. The bottom bird is regular along 'my' stretch of the river at present.