Whoever has released recorded conversations with unwitting National MPs at the cocktail function at their party's annual conference last weekend probably believes the ruse serves a public interest. The country now knows, if it did not before, that National has compromised some of its policy desires for the sake of its electoral prospects.
The party's loose-lipped deputy leader, Bill English, chatted amiably into the hidden tape about his leader's limited grasp of family benefits and of selling Kiwibank "eventually", while Lockwood Smith contemplated doing more in power once a National government had gained the public confidence.
As revelations go, these are rather less remarkable than the method by which they were obtained. Discreet recording is done but not commonly published by ethical news organisations for two reasons.
First, it is not fair to release a reporter's tape or transcript unless the subject denies something plainly said or the recording could serve a public interest somewhat more compelling than partisan politics. Second, the publication would damage the gathering of further information. Once bitten, a public figure is twice shy.
Nothing revealed from National's conference sneak so far offers insights to its intentions that could not have been obtained by a journalist trusted to use a private conversation responsibly.
That includes the comment on Kiwibank. Invited to contemplate selling it, Mr English's exact words were, "Well eventually, but not now.
Well, it's working. A lot of our supporters get a bit antsy about it, but it's working." In the circumstances, a fair report would say National's finance spokesman favours keeping the bank for the time being but seems open to selling it eventually.
If National's conference mole was working for the Labour Party, as National supposes, it is a new dimension to desperate politics in this country, and readily copied. All parties will know how easily opponents could plant an observer in their conferences capable of circulating at the tea break and engaging leading figures in candid discussion of sensitive issues.
Few targets might be easier than National's current deputy. Off the record, Mr English revels in mischievous comments such as those recorded about his leader, John Key, at the weekend. Mr English led the party briefly and, still young, might hope to do so again. His performance in the coming election will be interesting. If it is less than whole-hearted, and prone to confuse the party's message, it would not be the first time a party's campaign has suffered from an ambitious deputy.
But comments obtained by false pretences tell us nothing about Mr English's intentions. If he is of a mind to ensure Mr Key does not lead the party too comfortably he would drop some poison in a place he could control, not in someone's concealed microphone. This device has caused him as much embarrassment as his leader - not a bad return for the Government if it was behind it.
The Labour Party appears convinced Mr Key has more drastic economic policies in mind than he will admit before the election. Would that it were so. The more safely Mr Key is playing the game at present, the more genuine his caution seems. And Mr English is even less daring. He led National back to centrist conservatism after the defeat of the Shipley Government and he would keep it there for the time being.
He will be chastened by the concealed recording, and politicians of all sides will be extremely careful from now until the election. They will be wary of discussing sensitive issues with strangers. Such is the public price of a dirty trick.