It's not often that John Humphrys conducts a genuinely illuminating interview, but he did so this morning (1'10" in) with Neil Kinnock and Michael Gove - albeit perhaps inadvertently.

The revealing thing here is the self-congratulatory matiness. Three old boys are having a laugh together, even including a rape "gag"*. It's like a bad golf club. This reminds us that the political class - some of the Labour party (thankfully less than in the recent past), the Tories and top journalists are, essentially, all on the same side.

This smugness hid the fact that there are genuine problems with the BBC's interviewing; in fairness, Gove hinted at one when he said there as too much focus on the Westminster soap opera and too little on policy.

To see a couple of these problems, contrast that interview with Monday's exchange between Justin Webb and Angela Rayner (1'52 in).

I counted nine interruptions in six minutes. If we compare that to the chumminess of Humphrys with Kinnock and Gove, and to Webb's own failure to challenge Lord Lawson's falsehoods on climate change, a picture emerges - that BBC presenters are deferential to insiders such as old white men but more hostile to outsiders: how dare a working class woman like Ms Rayner have the temerity to enter politics?

Yes, the BBC has admitted that Webb's interview with Lawson breached its own guidelines. But is it really a coincidence that such an insufficiently rigorous interview should have been conducted with a posh old right-winger rather than with (say) someone working class, or black or a woman? (Note in this context the Today programme's consistent deference towards "business leaders".)

Secondly, note the perspective from which Webb is challenging Ms Rayner. It's from the "government as housekeeper" view. To his credit, Webb didn't sink so low as to ask "where's the money coming from?" but the presumption that Labour might spend too much on education is there.

This left another set of questions unasked. We might ask Ms Rayner: How can it be fair that some young people get two or three times as much spent on their schooling as others? Why is Labour so slow to narrow that gap? (State spending per secondary school pupil is £6300 per year, whereas day fees at Justin Webb's old school are £15570 pa.) Or: Given that the government can borrow at a real rate of minus 1.5% pa, any education spending with a non-negative real return has a positive NPV, so why isn't Labour planning to spend even more? Is it failing to take up positive investment opportunities? Or could it be that its spending won't in fact be so productive?

That such questions went unasked in favour of a perspective that is (to say the least) questionable demonstrates that the BBC does have a bias - a bias against radical questions. This corroborates Tom Mills' point, that "the BBC will aim to fairly and accurately reflect the balance of opinion amongst elites." Or as Cardiff University researchers put it (pdf):

The paradigm of impartiality-as-balance means that only a narrow range of views and voices are heard on the most contentious and important issues.

This, though, is not just unbalanced, but also a way of excluding and alienating outsiders - not just women (that rape "gag") but also the working class, minorities and, we might add, the economically literate.

* Right after that comment, Gove said that "you can make a fool of yourself" in radio interviews. He wasn't wrong.