If ever you wanted proof that the news you read arrives through a white filter - that it is selected, reported, edited and interpreted by groups of people that are overwhelmingly white - then the coverage of the departure of Sir Ian Blair from the Metropolitan Police Service provided it.
Let us set aside the Daily Mail (though in a sense it set itself aside by an eccentric insistence that its own reporting caused Sir Ian to resign). The Mail's hatred of the Met's commissioner, and its loathing for all realistic efforts to deal with racism in the police, are so pathological that no one would have expected coverage that was any different from what we got.
But why would Simon Jenkins, writing in the Sunday Times, feel it necessary to raise, in his critique of Sir Ian, "the over-promotion of non-white officers"? Does he have evidence that non-white officers have been over-promoted in the Met? He offered none, and it was telling that the very next day Mike Fuller, chief constable of Kent Police (he's black, but has four university degrees; is that enough?), declared that ethnic-minority officers have to work twice as hard to gain promotion.
The problem with Sir Ian, so far as I could see, was not one of over-promoted black officers, but of an over-promoted white one. But did Jenkins think before he wrote his throwaway words that they would contribute to prejudice against every black or Asian officer who gains promotion? Or did anyone at the Sunday Times say: "Hey Simon, got any evidence for that?" No.
Henry Porter in the Observer could not resist complaining that Sir Ian was "insufferably PC", a view shared by the Sunday Telegraph, which wrote of "the PC PC". What do they mean?
Four years ago Lord Morris, the black former trade union chief (and now you might be wondering whether Lord Morris was ever over-promoted; see how it works?), led an inquiry into a range of employment problems at the Met, including some relating to race, disability and other (to use the PC term) diversity issues.
This was, in turn, five years after the Macpherson report into the Stephen Lawrence case, which had prompted a great deal of public hand-wringing about the intolerant internal culture of the Met, even from the Mail.
Morris found some complex problems. The Met's formal policies were good, but the implementation was weak and confused, while the enthusiasm to get things right faded as you went down through the ranks. Diversity was "at worst, a source of fear and anxiety and, at best, a process of ticking boxes". And there were the beginnings of a backlash.
A survey of the Met's officers and staff, commissioned for the inquiry, found that barely half believed that their own force treated people equally and regardless of ethnicity, gender, sexual orientation, age or disability. Barely half - and that was the Met's own people.
Sir Ian Blair, who took office soon afterwards, had no choice but to make a fuss about these matters. But if, as an employer or public figure, you are seen to take diversity seriously, if you are fastidious about the interests of ethnic minorities, lesbians or people in wheelchairs, that makes you "insufferably PC".
You need action as well as words, but the words are indispensable. If the next Commissioner of the Metropolitan Police fails to say clearly and publicly that he or she will not tolerate sexism and racism, then the backlash Morris detected will have succeeded. With the connivance of all those comfortable hacks who find political correctness a bore, we will be back where we were in 1993, when Stephen Lawrence was murdered and the police could do nothing right.
Sir Ian Blair blotted his copybook with the press early in 2006, when he said he detected institutional racism in the coverage of murders. He had a point, even though he made it with characteristic clumsiness. But that point was never really considered by the people to whom it was directed, still less by their readers. Instead, we had panicky denial, howling and bluster; the story jammed in the white filter.
A few weeks ago in the Guardian, Max Hastings recalled a time in the 1990s when he became concerned at the "embarrassing whiteness" of the newsroom over which he presided as the then editor of the Daily Telegraph. That whiteness was typical of the industry, and things have changed depressingly little since then. It is not embarrassing but shaming, because of the complacency it reveals in an industry of cultural and political importance that remains a stranger to diversity and likes it that way.
When Greg Dyke observed that the BBC was "hideously white", he was - naturally - denounced as insufferably PC. But his phrase fits the British news business like a glove.
Brian Cathcart is professor of journalism at Kingston University