Helen Clark's long reign as New Zealand's Teflon Prime Minister is over. With a leader who resorted to Nixonian tactics to push Police Commissioner Peter Doone out of office six years ago, it must be galling for him to watch a successor open the criminal investigation that Clark had repeatedly emphasised was not warranted into Taito Phillip Field's actions.

It's not the timing that will give the Prime Minister any grief. Cynics are right to say that Commissioner Howard Broad's announcement on Thursday could not have come at a more convenient time for her.

Labour has been taking a pasting in the opinion polls as it tries to deal with the fallout from the Field affair and the scandal over the misappropriation of $400,000 in funds from Clark's own Leader's Office budget to pay for last year's election pledge cards.

Earlier in the week, Field refused Clark's prompting to jump from her sinking ship so Labour could recover its reputation.

But behind the scenes there have been direct complaints to Police Minister Annette King and Police HQ about Field's actions, coupled with hyperbolic allegations that the relevant players were conspiring to shut the issue down; a notion that would be dangerous to the body politic if it got wide currency.

Broad has effectively kicked into touch for now a fiasco which has made parliamentary question time a repeated exercise in embarrassment for Clark and her senior Cabinet Ministers, who were failing miserably to defend the indefensible by saying that Field, who had ripped off defenceless Thai nationals, had paid a sufficient price by being dropped as a minister.

Field has conveniently been ordered to stand down on full pay while the investigation proceeds. From now on National MPs will simply be told to take any new evidence - which they believe strengthens claims that Field used his influence corruptly on immigration issues - straight to the police. So that particular political sore has been cauterised.

What will gall Clark is the fact that the public, news media and Opposition politicians will not accept anything other than a rigorous police investigation into the Field affair and charges laid if prima facie breaches of the criminal code are established.

The police are facing a huge credibility issue. Six weeks ago Police HQ told me they had ruled out investigations of their own into the serious issues raised in QC Noel Ingram's lengthy report into Field's actions. Now Broad says they have decided to investigate Field as a result of issues raised during the Ingram inquiry. This is an absurdity.

Let's recap here. Ingram's hands were tied by the ridiculously narrow terms of reference dictated to him by Clark when she ordered the inquiry after the election. These focused on whether Field had abused his ministerial status when pushing for a Thai overstayer to get immigration approval without admitting the immigrant was providing cheap labour to tart up his Samoan house.

That, when it was obvious fairly early on that it was not Field's ministerial status that was the issue but the way he used his privileged access as an MP to successfully push the Thai's barrow with his ministerial colleague Damien O'Connor.

Ingram's report revealed he had suggested to Clark that more investigations by the appropriate players - armed by powers not available to him - were now needed.

But six weeks ago neither Clark nor the police would entertain Ingram's clear steer.

The apathetic police have since been shown up by the journalistic digging of Herald deputy political editor Ruth Berry, who quickly confirmed that the Field family lied to Ingram over the arrangements they made to employ Sunan Siriwan to tile their Samoan house.

TVNZ's Sunday programme, again armed with fewer powers than the police, lined up shotguns of its own to add to Berry's smoking gun.

There are other layers to this affair. Clark's relationship with the police is a complex one. She was investigated over Paintergate, but a forgery charge did not ensue despite a prime facie case against her. But she has hardly been generous in return.

It is particularly apt that Broad's announcement was made on the same day that High Court judge John Priestley quashed convictions for dangerous driving against the two policemen from Clark's motorcade who were charged after breaking the speed limit while getting her to an airport to catch a plane to get to a rugby test.

Clark left the pair to be hung out to dry when she could have defended their speeding as a misguided interpretation of their role in conveying her on public business.

Contrast their fate with the protective blanket she threw around Field.

The election funding scandal is still in play. Again the police cut the Clark Administration huge slack when confronted with a referral by the former chief electoral officer on the matter. A private action has been filed against Clark and there are suggestions that a well-known millionaire is prepared to fund another against Labour if it fails to pay back the misappropriated funds as the public wants - if a plaintiff of convenience can be found to front the action.

All this points to a major loss of confidence in the police and in the Prime Minister. Unless she meets the public's demands for a higher ethical standard from her Administration, she will face the consequences when Labour is turfed out of office at the next election.