The Duchess of Cambridge is a shop window mannequin whose only purpose is to breed, double Booker Prize winner Hilary Mantel has said.
During a lecture at the British Museum the author launched a scathing attack on the pregnant duchess, claiming she has no personality and a plastic smile.
The lecture, which took place two weeks ago, was organised by London Review of Books, a month after her latest novel Bring Up the Bodies won the Costa prize.
Entitled Royal Bodies, the lecture was on royal women in the public eye across history.
Mantel, who was awarded the CBE in June 2006, contrasted Kate Middleton's appearance to Princess Diana, "whose human awkwardness and emotional incontinence showed in her every gesture".
She said the Duchess was unlike Anne Boleyn, who was "a power player, a clever and determined woman."
She said the Duchess of Cambridge "appeared to have been designed by a committee and built by craftsmen, with a perfect plastic smile and the spindles of her limbs hand-turned and gloss-varnished".
The author also said: "These days, she is a mother-to-be, and draped in another set of threadbare attributions.
"Once she gets over being sick, the press will find that she is radiant. They will find that this young woman's life until now was nothing, her only point and purpose being to give birth."
The Derbyshire-born writer, whose other works include Wolf Hall, A Place of Greater Safety and Giving Up the Ghost, said the Duchess was "as painfully thin as anyone could wish, without quirks, without oddities, without the risk of the emergence of character".
Mantel also made known her views on the private photographs taken of the pregnant duchess on holiday: "The royal body exists to be looked at," she said.
"Some people find them endearing; some pity them for their precarious situation; everybody stares at them, and however airy the enclosure they inhabit, it’s still a cage."
The duchess, who was treated for extreme morning sickness in December last year, is expected to give birth in July.