His patience nearly exhausted, Michael Cullen spoke through gritted teeth as he spelled things out in single syllables for National's benefit. There had been no, repeat no, ministerial cover-up of the investigation into Mary-Anne Thompson and its findings.
National was simply trying to dig up non-existent dirt. It was talking paranoid rubbish.
Try as he might, Dr Cullen's assurances to Parliament on Wednesday were never going to negate National's assertion that Cabinet ministers were aware of the improper conduct by the head of the Department of Labour's Immigration Service for months but did nothing about it until public exposure of that conduct forced some action.
It would be going far too far to say there has been a cover-up by ministers in the normal meaning of the term - a deliberate and sustained attempt to conceal what has really been going on.
But neither did those ministers go out of their way to reveal what had been going on.
Neither the Labour Department nor the State Services Commission felt any compunction to inform the public of last year's inquiry into what was an astonishing breach of public service standards by someone running a major branch of a Government department.
Were it not for some concerted digging by journalists, the public would still be completely unaware of Ms Thompson's blatant conflict of interest in filling out residency application forms for close relatives.
She would still have her job.
Once the details of the Thompson affair broke, the two Cabinet ministers who already knew about the investigation inevitably looked complicit in officials' inept and shoddy handling of the matter.
This has been an appalling week for Labour, with high-profile job losses, appalling retail sales data, the failure to be totally upfront about how much was paid to buy back the country's rail services, further equivocation from Dr Cullen on tax cuts just days before the budget, and yet another poor opinion poll.
What ministers knew about Ms Thompson has been the politically-tasty icing on the cake for an Opposition spoiled for choice.
All week National has said Labour was being party to a "cover up", to reinforce its wider message that Helen Clark and company cannot be trusted.
The bonus for National is that two of Labour's newer and more effective ministers are at risk of being tainted by having held the immigration portfolio - Clayton Cosgrove currently and David Cunliffe prior to him.
Both were briefed by Labour Department officials on Ms Thompson's actions - Mr Cunliffe in April last year and Mr Cosgrove in December, after he became minister.
Should they have done something? Mr Cunliffe has said little and seems to believe he can ride out this storm.
As the incumbent, however, Mr Cosgrove has to front. He has quoted section 33 of the State Services Act as the reason he did not intervene.
That section requires that chief executives of Government departments must act independently of ministers when it comes to disciplining or sacking staff.
Mr Cosgrove's line is that he could not interfere in employment matters and Ms Thompson's actions were an employment matter. End of story.
But it is not that simple.
State Services Commission papers offering guidance to chief executives stress it is appropriate for them to consult their ministers on "personnel matters of significance" or about staffing matters "likely to become an issue of public concern".
Such briefings have to be initiated by the chief executive and avoid any suggestion that he or she has not acted independently.
Presumably, Mr Cunliffe and Mr Cosgrove were consulted on that basis. How much were they told? And was it enough to ring alarm bells and call in the State Services Commission as the body with the responsibility to sort things out?
Mr Cosgrove says by the time he was briefed by the Labour Department's new chief executive, Christopher Blake, the commission was already involved.
It is not clear when it did get involved, however.
Mr Cosgrove also says he was never shown a copy of the report by David Oughton, the former secretary of justice, who undertook the inquiry into Ms Thompson's lapse of judgement.
Had he seen it, Mr Cosgrove might not have been so willing to stay mum.
The report raises more questions than it answers, not least in clearing Ms Thompson with little explanation as to why Mr Oughton took that view.
Regardless of what Ms Thompson did or did not do, Mr Oughton's concerns about the handling of residency applications from the Pacific Islands by the Immigration Service's Manukau office cried out for further investigation.
Had Mr Cunliffe and Mr Cosgrove known all this, they might not have been so willing to accept that Ms Thompson's actions were solely an employment matter, and they might have taken steps to have the whole affair or aspects of it reviewed again, and this time with the public being told.
Public interest considerations clearly overrode Ms Thompson's rights to privacy.
The flurry of investigations and reviews now under way following public exposure of the case are a pretty good indication that the public interest was being ignored and the whole affair was handled badly.
This was not a case involving some faceless low-level bureaucrat.
Ms Thompson was a seasoned official who was on a $200,000-plus salary and operating at a level just below chief executive.
The Labour Department, however, took a "what they don't know won't hurt them" attitude to the public, rather than coming clean and fesssing up to the embarrassment and placing it firmly in the public domain.
If it is the State Services Commission's job to engender public confidence in the public service, how can that happen if things that are embarrassing to a department, an employee, or a minister, are kept secret? Of course, the public may have never known.
But that is not a satisfactory defence.
And, anyway, the Labour Department was unlikely to get away with hiding what had happened forever.
Ms Thompson - said to be imperious and inflexible - made too many enemies.
Sooner or later, inside knowledge of the Oughton investigation was going to leak out - just as Ms Thompson has been rumbled over her non-existent PhD from the prestigious London School of Economics.
The only surprise is that in both cases it took so long to happen.
When the story did leak out, the Labour Department continued to fight a rearguard action by blocking the release of the Oughton report.
When that failed, the department released it without forewarning on the Thursday evening prior to the long Anzac Day weekend in an attempt to minimize news coverage.
Such cynical, butt-covering behaviour demonstrates a contempt for the public's right to know.
That action alone should have brought the State Service Commission down on the department like a ton of bricks.
However, as long as the commission continues to function in namby-pamby fashion, the culture of secrecy and obstruction will persist.
The commission's forthcoming report on the Labour Department's handling of the Thompson affair will therefore be a litmus test of whether the new State Services Commissioner, Iain Rennie, is a new broom or just the same old flannel. - John Armstrong/ The New Zealand Herald
