The decision by Channel 4 to broadcast next Monday Diana: In Her Own Words has raised a storm of criticism. The documentary features video tapes of the Princess of Wales dating from 1993-1994 in which she speaks frankly to her voice coach, Peter Settelen, about the intimacies of her private life and failed marriage, her husband's relationship with the then Camilla Parker Bowles and the alleged coldness of the Queen.
The concerns are legitimate. Should they choose to tune in, the broadcast will be awful viewing for her sons, Princes William and Harry, who would have to endure the sight of their mother pouring her heart out. They'd hear her talk about her infatuation with her bodyguard, Barry Mannakee: "I was always waiting around trying to see him. Um, I just, you know, wore my heart on my sleeve. I was only happy when he was around."
Some of the revelations are toe-curlingly personal - like Diana's claim that she and the Prince of Wales had not had sex for seven years, or that Charles was "all over me like a bad rash" when courting her and that when first married they made love only every three weeks or so.
And, of course, the documentary will also give another outing to her hurt at Charles' betrayal: "I remember saying to my husband: 'Why, why is this lady around?' And he said: 'Well, I refuse to be the only Prince of Wales who never had a mistress.'"
Many have huge admiration and affection for the Queen, yet they will hear of Diana's dismay when she broached her unhappiness with HMQ: "So I went to the top lady and said: 'I don't know what I should do'. She said: 'I don't know what you should do. Charles is hopeless.' And that was it. That was 'help.'"
The febrile context here is salutary. Andrew Morton's book Diana: Her True Story had been sensationally published in May 1992, virtually blowing a hole in the marriage and in the image of the monarchy.
Later that year tape recordings of both Diana and Charles were leaked to the Press - Diana embroiled with James Gilbey in the 'Squidgygate Tapes' in August - and in November the infamous Camillagate Tapes, exchanges between Charles and his current wife.
By December the Prime Minister John Major was announcing their "amicable separation"; by January 1993 the excruciating full transcript of the Camillagate material was in the newspapers.
With the conflict in the open, both sides mustered their supporters, a process in which the prince had, naturally, all the advantages. A beautiful face is no defence against prestige, favour, power and the crown. It was, by turns, painful, embarrassing and gruesome and heading inexorably, as we see now, via ghastly mis-steps and misjudgments and gauche affairs and snubs, to that dreadful denouement in the Paris underpass.
Unsurprisingly Diana's brother, Earl Spencer, friends such as Rosa Monckton and former royal advisers including Dickie Arbiter are calling for the documentary to be shelved as a tawdry, money-grubbing exercise.
But Diana Inc has been trading at full pelt in the 20 years since her untimely demise - just as it did during her too-short life.
Her butler Paul Burrell, former beau Captain James Hewitt, ex-bodyguard Ken Wharfe and an assorted array of astrologers and hangers-on have all cashed in.
Diana made the careers of Morton and Bashir. She has been the subject of at least one major motion movie and some made-for-TV atrocities.
And let's not forget all those tomes from Charles's point of view. Or indeed Camilla's.
Highbrow or lowbrow, all of them telling the 'truth', 'putting the record straight', preserving 'the Diana I knew', all of them with a fat cheque in the post.
Little wonder then that her voice coach felt he could cash in too - though it must be said this is a particularly odious betrayal. But Diana will have had the same expectation of confidentiality when she let slip her emotions to trusted staff, friends and hangers-on.
And even she had a right to privacy. Though she is dead and so 'fair game', due to her imprudence and vulnerability at the time, the character of a loathsome toad will follow Peter Settelen through the rest of his miserable life.
Certainly betrayed and undermined by Charles and his advisers, she girded her loins and threw herself with a will into the limelight. Not for mere vanity, but because she was a wronged woman with nowhere else to turn but to the court of public opinion. She did so thrillingly and brilliantly, changing forever how we saw the Windsors and, more importantly, what we expect from the monarchy.
Her courage in taking her bleeding heart to the public is precisely why she is a cultural icon, right up there with Elvis and Marilyn.
If she hadn't cultivated the media, developing relationships with influential editors and prominent journalists, we would never have known about Charles's infidelity.
The painful truth for its critics is that there wouldn't be documentaries like Diana: In Her Own Words if there were no demand for them. Twenty years on, Diana still grips the imagination of the public.
Recent developments, such as Harry's dedication to charitable activities and the two brothers' own touching tribute to their mother's love, show that these are not children anymore. They are young men, both worldly and with a mature understanding of the ghastly messes relationships can land all of us in.
We forget how quickly it all happened. The couple were separated in December 1992, the Bashir interview was 1995, the divorce in August 1996 and her tragic shocking, death in August 1997.
Had she been spared, who knows what role she'd have found in her children's lives? Older and wiser, she certainly would have remained a friend to the Company, as the monarchy styles itself, and committed to those charitable and sometimes unpopular causes towards which her genuine compassion drew her.
She'd have remained a compelling and beautiful asset to the nation as a whole. She'd hate the idea of her sons being mortified by private recordings from the distant past.
It might all have been so different. That it wasn't was due to that old curmudgeon, human nature, which makes fools of us all. Not everyone will leave such spectacular evidences of poor judgment behind to embarrass future generations. Not everyone will feel that any person should be protected from their own flaws.
But sometimes, just once, you'd like to think that a woman is due some measure of privacy, especially one as put upon and as out of her depth as Diana was then.
Beautiful people often don't need to do anything at all to be cherished and have their memory honoured.
Just be beautiful and be loved by her children.
I think she qualifies royally on those grounds.