John Key says he's not worried that no proper work has been done to quantify the cost to taxpayers of a new flag.

It's just a week until the flag referendum ends, and Winston Peters has won an early battle to keep the current one.

Winston Peters is on the war path in Whanganui -- rallying his Grey Power troops, accusing the Government of fiscal mismanagement over the flag.

The Government has admitted it has no idea how much a flag change will cost if the fern wins.

The only work it has done is this estimate -- $2.7 million, just to replace 1500 flags and alter military uniforms.

There's no costings whatsoever for drivers' licences, passports, police, fire, and military flags -- or even things like lapel pins.

Mr Peters says it's "totally irresponsible", but Mr Key is unperturbed.

"I think in the scheme of things, it's not a big deal," Mr Key says.

The Prime Minister argues a change would boost the tax take.

"We have to produce them, GST gets charged, someone manufactures them, almost certainly locally."

And a victory today for Mr Peters on the flag -- two weeks ago, he hijacked an abandoned flagpole at Parliament, flying the national flag. Security took it down and returned it.

But it's since been replaced with an even bigger one -- an admission it should always have flown there.

"Sanity is starting to return to the Parliamentary complex," Mr Peters says.

All this while the final referendum's running -- so how's it tracking?

In the first referendum last year, just over 1.5 million people voted, a turnout of 48 percent.

And with a week to go in this vote, more than 1.6 million have voted -- 51 percent of enrolled voters.

Voting on the flag officially closes at 5pm next Thursday.

The preliminary result will be out that night, right at the start of the Easter break.

Newshub.