If you thought the population debate couldn’t get any worse, you were wrong – very wrong.

Yesterday degenerated into a sort of “I’m Spartacus!” debate in which Labor, the Coalition and Mark Latham all sought to claim that the others were pretenders to the throne of King (or Queen) of Sustainable Population.

“I don’t think this is a immigration debate,” the Prime Minister told an interviewer. “I think it’s bringing into play issues about water, about soil, about city planning, about infrastructure and services, about getting skilled people where we need them.”

This was indeed a strange thing to say, given we only make new Australians by the old-fashioned way or by importing them. Gillard naturally wants to avoid being pressed on the issue of exactly what immigration levels a Gillard Government would set.

Scott Morrison decided to wade into the issue, risking a repeat of previous embarrassments when he got basic numbers about immigration wrong. Bear in mind that the Coalition’s idea of a population debate includes graphics with red lines from Islamic countries invading Australia. Morrison attacked Gillard for delinking the issues. But what would the Coalition do?

Well, there’s the problem – both Labor and the Coalition have exactly the same policy. Labor’s is to have Tony Burke conduct a review, which he has already set in train, to consider the issue of sustainable population. The Coalition’s is to have a review as well, by what it will rename the “Productivity and Sustainability Commission”.

The Coalition’s plans for the PC, by the way, are a nice demonstration that in the Australian Public Service, success is invariably punished with more work and more responsibility. The PC is one of the great legacies of the Howard years, a fine institution that is an invaluable source of independent, sensible economic advice. Because of this, it will be nixed by the Coalition and replaced with a “Productivity and Sustainability” body with a mandate to frolic around in environmental, social and resource issues.

This, sadly, has gone below the media radar – understandable, I guess, but it’s a crying shame the PC will be wrecked in this way to suit this current anti-immigration fashion that has blown like a waft of foul air through Australian public policy.

So both sides will hit the ground reviewing on population issues after the election. That gives them a neat way out to duck the hard campaign question of what they really want to do with immigration, which based on their rhetoric is slash it, and Australia’s economic growth prospects along with it.

But as if to show there’s no debate that can’t be dragged lower, in walked Mark Latham. On Sky News – which in the old days he would have bagged as the Tory Network – the Campbelltown Poltergeist accused Gillard of a “con job” and “fraud of the worst order” on the good citizens of western Sydney. “I’m Spartacus,” he insisted, saying that neither side was prepared to admit Australia really needed to cut immigration.

For all of Latham’s behavioural issues, he at least always had a reputation as an innovative policy thinker. In retirement, it turns out he’s just another member of the Little Australia brigade, playing in the shallow end of the gene pool with the likes of Dick Smith and Bob Birrell.

There’s good news, though, because according to David Speers, Latham is thinking of getting on Twitter. Outstanding, because there’s not enough bile and snark in the Twitterverse.