Bigotry, like poverty, is always with us. It is not often in this country that you come across open, unselfconsciously brutal bigotry, but it is always there somewhere, lurking in the most respectable of places, and sometimes it drops its mask and bares its vicious teeth.

Twice last week I was astonished by glimpses of this vindictive grimace. I had begun to think this country was largely free of the ideological hatred and class war that so disfigured it in the 1960s and 1970s. Even the ban on foxhunting has failed. But now I realise that impression is all too superficial. Bigotry will out, and it wants to condemn, punish and control. It is the mindset of the totalitarian.

The Guardian published a column by Zoe Williams on Tuesday that ought to make any right-minded person gasp with shock, no matter what his or her political views. Quite a few Guardian readers were indeed shocked, to judge by their comments online. Williams was discussing the fact that many parents who would prefer to send their children to private schools – she calls them privateers – are obliged by the economic slump to send them to state schools. Her view is that the children of such privateers should be forced to the bottom of the waiting lists for state primary schools.

Never mind, she says, whether such children are “swamping” state primaries, or might do in the future, or not at all: this has nothing to do with the availability of school places and everything to do with ideology – such children must be put at the back of the queue. Her view, unpleasant though it is, might be worth rational discussion. But Williams’s tone is far from rational. It is frightening. She writes like an old-fashioned class warrior who believes children must be punished for the class guilt of their parents, and if that sounds vindictive, she admits she means it to. “Ha! Good,” she exclaims unselfconsciously.

Perhaps this is an opportune moment to point out that Williams was privately educated at the expensive and selective Godolphin and Latymer school in west London, which no doubt helped her to get a place at Oxford and a job at The Guardian; should she, too, be punished for the class crimes of her parents in educating her privately? Which queue should Williams be shoved to the back of to atone for her inherited class guilt?

What horrifies me more than her general approach is the totalitarian detail in which she indulges her class hatred. Her list of exclusion for privateers’ children is precisely graded. To the bottom she dispatches those who have been recently removed from private schools; “above them but below everybody else” should be children with siblings at private schools; and somewhere near them should be children whose parents’ first choice was a faith school.

It reminded me at once of the careful protocols of Nazi selection systems, or the elaborate plans put forward by Stalinists and Maoists; it reads like those chilling, heart-rending accounts of life in the USSR and communist China, from Solzhenitsyn to Jung Chang.

“There are other questions”, Williams goes on, apparently ignorant of similar interrogations during the worst of 20th-century totalitarianism, that “an admissions process could use to whittle out privateers. Do they have a 4x4? Can parents provide a letter from any local left-wing organisation attesting to their commitment to open-access state education? Did they go to any meetings? . . . come on, you lefties . . . what happened to your sharp elbows?” I rest my case. This is hate speech, class war and political bigotry of the most vicious sort. What is one to make of the suggestion that “local left-wing organisations” should stand in judgment on parents and their thoughts?

Just as astonishing was a comment made in a guide to adoption published by a state-funded national agency, the British Association for Adoption and Fostering. Its new booklet, the Pink Guide to Adoption for Lesbians and Gay Men, describes people who oppose gay adoption as “retarded homophobes”. The association repeated this choice phrase on its Be My Parent website, although it has since been removed. This again was a shocking glimpse of the unmasked teeth of vicious bigotry, made even worse by unselfconscious hypocrisy.

“Retarded” is a word that no decent person would now use to describe another. It was a cruel and largely American expression for people with intellectual impairments. For years it has been considered inaccurate, ignorant and offensive and demeaning to people with learning disabilities.

I find it amazing that anyone would use it at all, let alone in public or in print, let alone the people in the adoption association, which is about as politically correct as an organisation can be, and still less in a booklet aimed at a minority that has good reason to notice and resent demeaning words. It seems the phrase was written by a contributor, not by the association, but that is no excuse – the word “retarded” should have leapt out at those responsible for producing the booklet.

And how much worse it is to use the word “retarded” as a conscious insult. How can any outfit subsidised by the taxpayer and run by the supposedly politically correct use any disability as an insult? And how much worse again it is to use such bizarre insults against people to discredit their arguments and their beliefs. Does the association think that people who disagree with it are, ipso facto, “retards”? Is disagreement with it a sign of cognitive impairment? Does it perhaps think that people who disagree are not merely mentally handicapped (in another old-fashioned expression) but mentally ill as well, in need of locking up in an insane asylum as in totalitarian countries?

Whether people who oppose gay adoption are right or wrong is not the point. I happen to think they are wrong, but it will not do to dismiss their arguments with insults – insults that are not only offensive to them but also even more insulting to innocent bystanders. I am glad, however, that these bigots have done so, because those who wrote these words and published them and publicised them on the internet have revealed themselves in their true colours.

For the same reason I am glad that Williams felt free to publish her spiteful rant and that The Guardian printed it. By their words shall ye know them. That is one of the great beauties of free speech. If we must have bigots and totalitarians in our midst, it is good to know who they are and what they think, so we can beware of them.

minette.marrin@sunday-times.co.uk

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