Editor's note: Robert Jobson is an award-winning royal correspondent and best-selling royal author, whose books include William & Kate: The Love Story and Harry's War (biography of Prince Harry), both published by John Blake.
Her remarks saying her impression of our future queen is that of a "jointed doll on which certain rags are hung," with a "plastic smile" and "only purpose being to give birth," is mean spirited in the extreme.
Where does the double Man Booker Prize winner get this impression? Has she ever seen Kate up close or seen her interact with people at home and abroad?
I doubt it very much. If she had she would not have been so rude and inaccurate.
The darling of the literary establishment I fear is playing publicity seeking games; raising her profile on the back of one of the most famous women on the planet right now.
I respect Hilary Mantel as a writer. I like her books too. But she clearly knows very little about modern princesses -- or duchesses even.
Perhaps all that time writing about Tudor princesses has led her to lose her head -- like so many Tudor heroines.
Mantel has never met the duchess. She has never seen her at work. I have, and I have been impressed by the speed and ease with which she has taken to the job of being a front line royal.
People who meet Kate warm to her. She has a winning smile and easy charm. Yes, she has a long way to go, and is not the new Princess Diana as many in the media are hoping for.
But I think she is slowly but surely carving out a role for herself.
Even Diana took years in the job before growing into the global icon who was so admired before she was taken from us so tragically.
For somebody who is relatively new to royal engagements, Kate has performed with aplomb.
On foreign assignments too, I have seen her at close quarters in Canada, America, Singapore and Borneo. She is professional and warm, complimenting her husband Prince William as they carry out their royal duties together.
Kate and William are a great double act. There is her wifely strength, like the Queen Mother, and as a Queen Consort she does not try to steal the limelight from her husband.
The Palace and Kate have kept a dignified silence over Mantel's rant. It's a wise stance.
I know the team around Kate and far from her being a "machine-made doll" or "designed by a committee" she has a hands-on role in everything she does. They follow her lead.
She has chosen to be patron of charities in which she has a deep personal interest.
Kate, in the coming months and years, will let her actions speak for her.
Today she was back doing royal duties for her charity Action on Addiction at Hope House in Clapham, South London.
She looked fabulous as she stepped out of the royal car, happy to show her baby bump to the media gathered outside. She was well briefed and knew her stuff.
She is a beautiful, educated and stylish young woman, who has embraced her role with ease and injected much-needed glamour to the British royal family.
The Palace will step up the number of patronages in the coming months and claims that Kate is a plastic princess will soon fade.
Kate has her detractors -- many Internet trolls label her work shy -- but I am surprised someone of Mantel's stature has joined in this pastime, attacking Kate for no apparent reason.
In my view she has abused her position among the novel-writing elite to launch this astonishing attack on a woman half way through her pregnancy.
Mantel, whose latest books are set in the Tudor court, is lucky she is not a character in one of her own books. If she had attacked the wife of a future king back then with such vitriol she may have soon lost her head in a more literal sense.