Flashback: Winston Peters declares he's siding with Labour

It's one year to the day since Winston Peters announced his decision to form a new Government with Labour.

Speaking at the Beehive in Wellington on October 19, 2017, Mr Peters said siding with National would have meant a "modified status quo", versus "change" with Labour.

Despite weeks of waiting, the NZ First leader said he made the call only 15 minutes before telling the nation.

"This decision is owed to the New Zealand people, who put us here. Not to the politicians, but to the New Zealand voters," he said.

There was a cry of jubilation from Labour's floor of the Beehive as MPs watched Mr Peters make his announcement - it appeared to be news to them, too.

"We are both committed to forming a strong and durable Government that can deal with the many challenges this country faces," soon-to-be Prime Minister Jacinda Ardern said afterwards.

Then-National leader Bill English vowed to be part of the "strongest Opposition party that Parliament has seen".

Watch the video to relive the moment Mr Peters changed the course of New Zealand politics.