Need some expertise off air? Contact our Perth Tonight guests! I went on to quote Paul Barry, who said that whereas he was certainly to the left of Bolt, that didn't mean he was on "the left". In his conversation with Barry, Mark Scott had this to say: "You know, a lot of that criticism comes from right-wing commentators and they wonder where are the strong right-wing commentators on the ABC. We don't do that kind of journalism. We don't ask questions about our journalists' voting pattern and where their ideology are (sic). We look at the journalism that they put to air." Which is all very well, so far as journalists are concerned. I agree with Scott that most of the ABC's news and current affairs presenters and reporters do a good job of maintaining their impartiality – and much more importantly, so does a substantial majority of the Australian people. But much of the ABC's factual output is not, strictly speaking, "journalism". Talk radio audiences in particular are drawn to the personality of the presenters they favour, be they Neil Mitchell or Jon Faine, Alan Jones or Phillip Adams. And you cannot express your personality in a program that deals with political issues without betraying your own political leanings.

Credit:Jessica Shapiro (Well, you can, actually, as the late, great Andrew Olle demonstrated for years. I knew him quite well, and couldn't tell you which way he voted, and nor, I'll bet, could most of his listeners on 702 ABC Sydney. But he was a rare exception to the rule.) It's also undeniable, as the likes of Bolt and Henderson have complained for years, that the ABC's capital city radio presenters come across, overwhelmingly, as leaning more to the left than the right. I say "undeniably", but senior ABC managers for decades have chosen, if not to deny it, then to ignore it, and they've certainly failed to do anything about it. Michelle Guthrie became the first female managing director of the ABC in 2016. ABC managers too, it seems to me, have agreed not to explain why this is so. Yet there is a good commercial rationale: on AM radio in particular, it's where there's a gap in the market.

AM listeners are overwhelmingly over 40 – many of them a good bit older. Those to the right of the political spectrum are amply catered for by commercial radio. Indeed, it's even harder to find a left-wing presenter on commercial talk radio than it is to find a right-winger on the ABC. The political leanings of the ABC's regional radio presenters are much harder to determine, and that's not unconnected to the fact, I would argue, that in many places they are the only significant voices on radio dealing with serious local issues. To survive, they need to be able to attract listeners from across the spectrum. In the capital cities, getting decent audiences on ABC local radio for a host with rightish views would be hard. By being even mildly right-wing, they risk alienating the ABC's traditional audience. Over the decades, radio listeners have divided. If you favour the right, you go commercial; if you favour the left, you go to the ABC. If the ABC wasn't funded by taxpayer dollars, no one would mind this situation. After all, the population is split roughly in half over politics, and both sides deserve to hear their views expressed. But the ABC is publicly funded. It does have a legal obligation to not favour one point of view over another.

The leftiness of ABC radio output is doubly problematic when it comes to Radio National. It may not have a huge audience, but it doesn't have commercial competition. No other radio channel in the nation tries to cover serious issues in a serious way, for a national audience. And yet, if I were a supporter of Tony Abbott, or even of John Howard, I would feel that the vast bulk of RN's output was not for me. For decades, Coalition senators have been asking ABC managing directors at estimates hearings: "Where is the right-wing Phillip Adams?" The ABC's answer has been to give half an hour here and there on Radio National to the likes of Amanda Vanstone and Tom Switzer – neither of them more than mildly right of centre. Frankly, it is little better than mockery. (To be fair, it also appointed Patricia Karvelas – who's no lefty – to the drive slot on RN when Waleed Aly left for Ten's The Project) If Mark Scott's successor Michelle Guthrie decides she wants to tackle this issue, she'll have her work cut out. She'll be facing an entrenched culture within the ABC. Many of its staff genuinely think that most well-informed people think as they do. She'll also need to consider that those of right-wing opinions long since stopped listening to large chunks of ABC radio's (and especially RN's) output, and will be very hard indeed to attract back. But if the ABC is to survive and thrive, it needs to cater to the nation as a whole. In my view (though not in Andrew Bolt's), ABC news, ABC television and ABC online do that job reasonably well. But ABC radio needs to try harder.

Jonathan Holmes is a Fairfax columnist and a former presenter of the ABC's Media Watch program.