By Andrew Roberts
Camilla, Duchess of Cornwall, turns 70 today, an ideal time for a 12-year-old wrong to be righted. At the time of her marriage to Prince Charles on April 9, 2005, a jittery Palace - worried that she would be unpopular - announced that she would not be known by her rightful title of Princess of Wales. Humiliatingly, when Prince Charles becomes King she will only be known as the Princess Consort, rather than Queen Consort.
This unhistorical, unfair and almost unconstitutional treatment was meted out just as she was about to enjoy the happiest day of her life, by courtiers who feared the memory of Diana, the ex-Princess of Wales, who had died tragically eight years before, was still so fresh in people's minds that no one else could take her former title.
Yet under English law, wives take on the rank and status of their husbands on marriage.
There is one Royal precedent for this not happening, when King George VI refused to make the Duchess of Windsor (the former Mrs Simpson) an HRH when she married the former King Edward VIII after the Abdication.
Today, that is generally considered to have been a petty action against a woman who was despised because she was a divorcee (and being American had something to do with it, too). Yet fobbing off the wife of a King as a mere Princess Consort is far worse even than
what the Royal Family did 80 years ago.
The then Camilla Parker Bowles had an affair with Prince Charles. So what? Scores of senior Royals have had affairs throughout history, and the couple have now been very happily and faithfully married for more than 12 years. In the goldfish bowl that is Royal life and work, Camilla has undertaken her many and varied tasks perfectly.
She does a huge amount of charity work and has not put a foot wrong, which is more than can be said for some other members of the family. She has also been a superb stepmother to Princes William and Harry, who might have had a reason to resent her but instead adore her.
Her 70th birthday is the right time for Britain to acknowledge the happiness she has brought to the Prince of Wales, to start calling her by her proper title, Princess of Wales, and to scrap the embarrassing situation by which she will not become Queen Consort.
Diana, Princess of Wales - as she should by right be called, rather than Princess Diana - is now a figure belonging to history, as opposed to current affairs. A wonderful mother and tireless campaigner for good causes, her early death was undoubtedly a massive national tragedy.
But two decades have now passed since that terrible accident in the Pont d'Alma underpass in Paris, and her memory is now just that - a memory. It should not continue to introduce unnecessary anomalies into the British constitution with regard to nomenclature in the House of Windsor.
Since the 2005 announcement had no force of law, but was simply a statement made by Buckingham Palace without parliamentary involvement, it can be just as easily reversed.
The Queen is the Fount of Honour, and so could scrap the present arrangements overnight. No 10 would have to be consulted, but more in the form of a notification, and one suspects the PM has more pressing things on her mind than whether a dwindling band of Diana-obsessives might be upset by the alteration. People have to be in their mid to late 20s today even to have the most vestigial memories of her.
The title Princess of Wales is an ancient one, and it is absurd that its present use has been prevented by the over-sensitivity of courtiers 20 years ago.
The first holder who can be proved to have used the title was Eleanor de Montfort, the wife of Llywelyn ap Gruffydd, in the mid-13th Century, although there are historians who argue that other princesses might have been using it even earlier than that. Some of the great female figures of British history, such as Catherine of Aragon, Mary Stuart and Queen Caroline, have been Princesses of Wales, even if not all of them were formally invested with it.
King George VI only decided not to give the title to the present Queen because of the question of what her future husband would be called, which is not a problem facing the Duchess of Cornwall today.
The fact King Edward VII's wife Queen Alexandra, and King George V's wife Queen Mary, were Princess of Wales before becoming Queen Consort should be precedent enough for the Duchess of Cornwall. If it was good enough for the wives of Prince Charles's great-grandfather and great-great-grandfather to have their wives honoured, it ought to be good enough for his.
Royal titles are not awarded on the basis of sexual behaviour decades earlier - the scandalous Caroline of Brunswick is proof enough of that. We do not have the concept of morganatic marriage in this country as they do on the Continent, and this attempt in 2005 to introduce it by the back door now looks heavy-handed, old-fashioned and foreign to our usage.
Monarchy is about continuity, and the use of titles is a powerful element of that. It was welcomed when it was announced Prince Harry will be called the Duke of Edinburgh one day, not least as it will be a reminder of the sterling service to the nation of Prince Philip.
The title Princess of Wales cannot belong to any one individual in history, any more that the Dukedom of Edinburgh or Cornwall does, especially if the abeyance of the title was to appease a dislike of Camilla that has disappeared today.
It is true she was made a privy counsellor last year, which is a notable honour, but not one to equate with being allowed to use her rightful name.
Prince Harry has been given recently to discuss Royal issues in public, for good and ill. He and his brother would do an unqualified public good if they asked that the title once used by their mother could now be accorded to their stepmother.
It would make their father happy, and people simply won't understand having a King and Princess Consort at the next Coronation rather than a King and Queen. It would also be a mark of approbation from the House of Windsor to Camilla for a difficult job very well done.