Identity search

I saw this bird on my walk through the wetlands in early January:
DSCN2455
It’s clearly a duck or a goose.
I can’t find it in any of my Australian bird books.
Does anyone know what it is?
DSCN2456

Note:
Oops! Somehow I inadvertently published two posts today instead of my normal weekly single post. I must have got overexcited and hit ‘publish’ too soon! This means that there won’t be a post next week, but I’ll post again the following week.