MIRROR, mirror on the wall: that phrase has a grip on our times, supposedly reflecting the thoughts of all those tormented, envious older women who harbour feelings of bitterness and rage towards younger, more beautiful females.

Last week, the phrase was captioned on to the lips of Hilary Mantel in a Daily Mail cartoon, which cast the Booker-winning author as the envy-contorted queen. Mantel was depicted as fat, frumpy and gazing into the looking glass at the perky, smiling image of Kate Middleton, the Duchess of Cambridge.

The cartoon was published during a media storm about a purportedly "venomous attack" by Mantel on the duchess. This reaction was triggered by comments Mantel made weeks earlier, in a speech for the London Review Of Books, and used in a Daily Mail article under a headline that suggested she had dubbed the duchess "a plastic princess designed to breed".

If you read Mantel's essay, it's clear that she was not attacking the duchess personally, but describing the way the palace and the media treat royal women, in her case as "a jointed doll on which certain rags are hung ... a shop-window mannequin, with no personality of her own, entirely defined by what she wore".

An article by Julie Burchill, which backed Mantel, triggered further, similar comments, including: "Hilary Mantel and Julie Burchill don't like Kate because they are fat and she isn't."

Over the past few years, two big-budget Hollywood productions of the Snow White fairytale have been filmed. Clearly, this is a story with particular resonance for our times. We have seen versions of it surface in real life many times in recent decades. Many a spat or comment by one woman about another is interpreted in this way. Wasn't the Sun's decrying of Clare Short as a "fat and jealous" when she campaigned against Page 3 just another reworking of the Snow White envy theme? My own belief is that the "jealous older woman" notion is exaggerated and stoked by our culture. Older women are frequently much more sanguine and philosophical than is made out. In the Daily Mail last year, Louise Chunn, former editor of Psychologies magazine, wrote: "My own looks may have faded but I still admire young beauty - so stop painting us mature women as embittered old witches."

I also don't believe that there is any jealousy in Mantel's essay. She clearly does not covet the royal life and advises that we "back off and not be brutes" towards them. But also, when the only woman to win the Booker prize twice comments on the appearance and media representation of a princess, this is not envy. It's a statement and challenge to an orthodoxy that suggests beauty is all.

Meanwhile, there is also more to the saga than Snow White. This is a story about the way we treat older women who choose to say anything. Women over a certain age, probably around 50, should not only not be seen, but should not be heard. The internet has been the perfect platform for such attitudes. When Professor Mary Beard appeared on Question Time in January, she was subjected to a stream of vitriolic online abuse. Among the more printable comments was one which described her "as a vile, spiteful excuse for a woman, who eats too much cabbage and has cheese straws for teeth".

The London Review Of Books has caused controversy before, and more often than not they have involved women. Anne Enright's essay on Gerry and Kate McCann was similarly quoted out of context and triggered outrage and condemnation. Beard caused uproar when she wrote a post 9/11 piece saying America "had it coming". John Dugdale, writing in the Guardian last week, described this pattern of media outrage as rooted in the fact that the press has "a double stereotype to pounce on: not just bookish types straying dreamily into columnists' domain, but also, female intellectuals who supposedly despise less brainy women".

The idea that women fear, despise or envy other women is an old story and an ugly one. If we were to tell it about men we would simply say they were competitive: we would not imbue it with fairytale grotesquery. But where women are concerned, our culture too often makes out that this is all about the mirror. And, in doing so, it stokes antagonism, creating walls between women which may not otherwise exist.