It's
Guy Fawkes Night and they don't celebrate it here in Australia. What's up with that? Wikipedia reckons the "anti-Catholic connotations" are what stopped it here. It's funny, I don't recall us burning the Pope in effigy or distributing condoms outside Catholic churches in either NZ or the UK.
The fireworks in London are fantastic. They have big events in various locations where you can check out the displays, but the best ones are on the Thames. They have barges floating down the middle and let off TONS of fantastic fireworks. My favourite spot was standing on London Bridge (on my way home from work when I was working in the City), looking back towards Westminster. Although the view over towards Tower Bridge is just as good.
In NZ, they still sell fireworks to individuals, and I wish they wouldn't. The ones you can buy are pretty crap, since they've been watering them down over the years. But you still get horrible little boys tying them to cats and their grown-up equivalents setting fire to area of bush and various buildings. Other than sparklers, what's the point when you can look at big spectacular ones in a nice setting?
The best place to watch fireworks in NZ (that I've found so far) is in Wellington Harbour. It's a circular-ish bowl surrounded by steep hills, so you can find a good spot and the backdrop is spectacular.
See what I mean! (slideshow of shots uploaded of this evening's display in Wgtn, with the port in the foreground).