This week’s Wankley goes to a dual bout of disingenuousness between the upstanding director of the Sydney Institute, Gerard Henderson and fellow Fairfax columnist and former Liverpool Mayor Mark Latham.

Yesterday, Latham penned his weekly screed in The Australian Financial Review, in which he took Henderson — who he branded a “pedant” — to task for apparently misrepresenting Australian Electoral Commission data in this opinion piece published in The Sydney Morning Herald on September 7.

Henderson, Latham railed, had made an “error” in claiming that “over 80 per cent of electors still give their primary vote to one of the two major parties.” The former PM in waiting then used this to indulge one of his favourite topics — the dwindling legitimacy of the two-party political system in the face of widespread public disinterest.

Latham said that of the 14,088,260 Australians enrolled for the federal election, 4,711,363 voted Labor and 3,777,384 voted Liberal, “a combined tally of 60.3 per cent”. Which is obviously correct. Even with the other conservative parties added in — the Liberal National Party of Queensland, The Nationals and the Country Liberal Party, then the figure was only 71.8%, Latham said. Which is also correct. He added that the “percentage of electors who gave their primary vote to Labor” was 33.4%, “barely a third of the nation.”

Indeed, all the numbers are correct if you define “electors” as the total number people on the roll for the federal election, including the 6.79% of voters that failed to turn up. But Latham didn’t spell that out. Readers, including this morning’s Cut and Paste section in The Australian, were left wondering if the primary vote figures repeated endlessly in the media since polling day were wrong.

Latham was also being shifty on another count. The Liberal National Party of Queensland and the Country Liberals are divisions of the Liberal Party of Australia, so their combined 1,168,860 votes should have been included in the first Liberal Party figure.

Today, Henderson hit back on the Fin‘s letters page. But rather than explain the source of the discrepancy, he decided to increase the confusion, rehashing the AEC’s “First Preferences by Party” table. That table lists the first preferences as a percentage of the formal vote, rather than the “total number of electors” measure favoured by Latham. But Henderson, like Latham, decided not to explain the disconnect.

The Media Watch Dog columnist also failed to properly address Latham’s central allegation — that he was wrong in stating the “two major parties” received over 80% of the primary vote. On any measure, the words “two major parties” means the Liberal Party and the ALP. The Nationals, even though they have a non-compete deal with the Libs for most lower house seats — are a totally separate party. As Henderson admits, the ALP and the Libs’ combined primary vote — on any measure — is well under 80%.

At the conclusion of both salvos, the authors get personal. Latham makes the strange point that Henderson has a “vested interest” in perpetuating the current system because he regularly invites its representatives to speak at his Sydney Institute shindigs. Henderson accuses Latham of hypocrisy because he receives parliamentary superannuation.

But by then, The AFR‘s readers, sick to death of the pointless bickering correctly identified by Latham, would have lost all interest.