Barnacle Goose Branta leucopsis AC2E*
I'm not claiming Cat. A for the Nunnery Lakes bird - that would be stretching it - but a quick squint at BB 104 p122-123 gives me enough evidence to bag it on Cat. C, I reckon: "Barnacle Goose was added to Cat. C2 in 2005 based on self-sustaining populations in at least Bedfordshire, Norfolk and Suffolk." And a recent WeBS report put the winter maximum of 'naturalised' Barnies at a staggering (depressing?) 1,516 individuals in January 2009.
Now I'm sure there won't be any dissension at Mandarin (in Breck, they're as wild as the day is long... arguably not the best turn of phrase in January but hey-ho), nor today's plastic-fantastic addition: undisclosed golden bird sp. at undisclosed location 4 miles from home (87)!