Robert_Charlton - 12:45 am on Dec 28, 2008 (gmt 0)

edd1 - What else are you doing besides making the change in WMT? Do you have a .com or a .co.uk tld?

Make sure you have inbound links from New Zealand sites... ie, sites that do well in google.co.nz. I suspect that Australian links will help as well, but I'm not sure how Google slices up the territories down there.

You should also have localized New Zealand content on your site, including address info, phone numbers, NZ spelling where appropriate, etc.