Last week, I defended the BBC against Emily Bell’s challenge in The Guardian about the corporation’s impartiality. The post created a lot of interest, including a comment from Emily herself.

So it was interesting to see this week a report from the BBC about the challenge of safeguarding impartiality. It concedes that the BBC has made some high profile lapses, such as allowing the Vicar of Dibley to champion the Make Poverty History campaign. It also quotes Andrew Marr, the corporation’s former political editor, who argues that the BBC has an "innate liberal bias". No doubt Emily was smiling at the thought that the Beeb itself had, apparently, conceded her point. But the reality is more complex.

Impartiality has usually been seen as about party politics. While the Daily Mail routinely supports the Conservatives – with its party bias evident through the paper, never mind on so-called comment pages – the BBC has rightly had to stay above the fray. It was easier in the days of monolithic, two-party, Westminster politics. Today’s three-party, devolved politics are more complicated. But the BBC itself has created complications. It has long offered political comment as well as reportage, and Andrew Marr injected new levels of acerbic wit to political commentary. (His recent History of Modern Britain reminds us what we’re missing, while underlining the fact that this approach is more subjective.) This inevitably raises the impartiality stakes.

But Marr’s central point strikes me as the most sensible explanation about why the BBC often infuriates people of a certain persuasion. There’s no conspiracy. It’s just that many BBC people are inclined to liberal views, are likely to be suspicious of business and – as Marr suggests – come from predominantly urban areas.

Jeff Randall, the BBC’s former Business editor, put it nicely: "It’s a bit like walking into a Sunday meeting of the Flat Earth Society. As they discuss great issues of the day, they discuss them from the point of view that the earth is flat. If someone says, "No, no, no, the earth is round!", they think this person is an extremist. That’s what it’s like for someone with my right-of-centre views working inside the BBC."

Craig Oliver, the editor of the Ten O’Clock News, writes about the report and the issues raised on the BBC’s Editors’ blog.