Hi Copland, I'm certainly no expert but since you've asked for any ideas and for what it's worth...
I think the smallish bill doesn't really look like Snow Goose, or Canada Goose for that matter, the plumage doesn't look like Canada either. In my opinion it seems to more closely resemble the bill of an Emperor Goose, and at a push...the whole head looks Emperor-ish too. The yellow could also be explained by Emperor and look closely at the base of the neck, a beautiful scaly pattern that 'could' be down to Emperor. One last thing, on Google images, type in Emperor Goose hybrid and your first couple of images could provide some help to possible identification with an Emperor x Barnacle Goose hybrid that looks fairly close to yours.
Amongst the usual Canada Geese on the lake, there is a ringed hybrid goose, found on Thursday by Tony O'Mahoney. It is there again today. Maybe a Martinmere bird? Possible Snow x Canada, or Snow x Barnacle. The yellow on beak and legs doesn't seem to be on the Snow-Canadas I've looked up. Any ideas welcome.
11am No Shoveler, Merganser or Goosander. The usual Mute Swans, Canada Geese, Mallard, Tufted Duck, Coot, Moorhen. 1 Common Gull spotted amongst the Blackheaded.
2 pairs of Heron. One sitting in the south nest. 2 building in the north nest.
Same as Pete yesterday, but without the Shoveler. One Heron on the nest, another below on the island. Goldcrests and Nuthatches very active. Parakeets over.
Dawn today shoveler 2m 1juv m Buzzard over flying north Ringnecked parakeets. 2 flocks (23 & 15 AT LEAST) flew west of south at sunrise. Direction of Southern Cem & Chorlton WP
Just before 1100 2 male Goosanders came in, flew around the lake, then were lost to sight but they didn't land. Soon after 1 of the Goosander females departed east. The other female Goosander and Red-breasted Merganser remained.
I assume the Merganser is a female with it's bright red bill?
Red Breasted Merganser showing well at 1 pm. Diving constantly. Came up with a reasonably sized fish, promptly dived bombed by 3 Black Headed Gulls,but managed to swallow it ,thwarting the gulls.
Red-breasted Merganser 1. It took flight with 7 Goosander at 16.06 but split from the group as the others headed off south-east, circled the lake before heading south-west, back towards Platt Fields.
Goosander 13. First one at 16.02 then 7 at 16.06 flew south-east, presumably to roost at Broad Ees Dole, leaving 5 remaining at 16.20
Red-breasted Merganser 1. It took flight with 7 Goosander at 16.06 but split from the group as the others headed off south-east, circled the lake before heading south-west, back towards Platt Fields.
Goosander 13. First one at 16.02 then 7 at 16.06 flew south-east, presumably to roost at Broad Ees Dole, leaving 5 remaining at 16.20
At 4:30am today, female Tawny Owl heard calling in the Park (kevick) repeatedly, close to Demesne Road and then the calls receded further north. Magpies immediately kicked up a rattle of alarm calls that went on for nearly half an hour, although I didn't hear the owl again.
Counted approx. 10 Goosander on the lake this afternoon, 3 males and maybe 6-7 females/juveniles. Before I could confirm the count some dogs ran towards the lake and despite the barrier the birds got scared and flew off!