It's time we stopped insulting the Duchess of Cornwall

It is a shame that so much of our view of the Royal family should still be refracted through the definition of its role that was shaped, more arbitrarily than many realise, by Walter Bagehot in 1867. The English Constitution, in which he dismissed Queen Victoria and the Prince of Wales as "a widow and an unemployed youth", was a fine work of journalism: but then Bagehot was a fine journalist, prone to the witticisms we hacks like to share with our readers. His expertise on the constitution derived from observation rather than study, and there is nothing wrong with that. In defining the sovereign's three rights – to be consulted, to warn and to advise – he was close to the mark, though anyone who has read Queen Victoria's traffic with her prime ministers, especially with Gladstone, will realise that it was not a definition she would have swallowed.

Bagehot's work was (and still is) immensely influential, though its influence reduced the Royal family to the status of a living museum or variety turn. It was hardly surprising that this should have been so, because Bagehot wrote at a time when the Second Reform Act was reaching the statute book and there was a democratic mood abroad. Also, the Queen, still wallowing in hysterical grief six years after the death of the Prince Consort, was widely disliked – with, it must be said, good reason, given her wilful detachment from her people. Those conditions are now history, yet the gentle contempt with which Bagehot suggested educated people should treat the Royal family does, however, remain.

Nowhere is this better seen than in the regard in which the Prince of Wales and his wife are held. A generation above them, the Queen is deemed untouchable, such is the affection that her people have for her. No sensible politician or media outlet, wishing to court either popularity or an audience, will criticise her. A generation below, Prince William and his bride-to-be are the focus of increasingly cloying sentiment, which one knows from experience could just as easily turn ugly once people become bored with them. This, of course, happens to footballers, pop stars and actors. It is unfortunate that the role played by our Royal family, and future head of state, has been reduced to that.

For the Prince of Wales and the Duchess of Cornwall, things are more complicated. From the way the Prince is treated, anyone would think he had applied for his present position and – having seen off other, more worthy contenders for the post – chosen to do it in a way that consciously disobliged the public. He enjoyed a reasonable rapport with the rest of the world when a young man, doing a stint in the Royal Navy, and benefiting from the last reserves of residual deference. He was acclaimed for marrying a beautiful and glamorous young woman. He then became rather outmoded when she eclipsed him, and when it was learnt that all was not well in their marriage, he was accorded the blame. It is, it seems, quite in order for the rest of us to make judgments about the intimate affairs of people whom we do not know at all, while we so often choose not to make them about those we know exceptionally well.

His first wife's untimely death in the company of a degenerate playboy threatened to terminate his relationship with his future subjects, or so one would have gathered from the media coverage at the time, which built him up as an unfeeling monster who had done everything to drive Diana, Princess of Wales to her doom short of actually sitting behind the wheel of the Mercedes himself. A sizeable minority of Britons became almost hysterical about this: not just in the days after the unfortunate accident in 1997, but for some time afterwards. Rumours went round on the day before his ex-wife's funeral that the police were on alert in case somebody tried to assassinate the Prince while he walked to Westminster Abbey. Nobody did, of course, and nobody was ever going to: the minority was unrepresentative. Most people, quite rightly, took the view that for all the public spectacle, this was private grief.

The minority view has, however, been pervasive. I have occasionally written that the Duchess of Cornwall is unfairly treated by some elements of the press and public. The result is to be bombarded with communications describing the Duchess in terms I thought had passed with the 18th century, and to vilify her for wrecking the Prince's first marriage. There is little to be gained by pointing out that none of us who was not there knows what wrecked it; or by alluding to the double standard that we all have in regard to friends and family members who have had often unpleasant divorces, and this does not inevitably stop us seeking their society and even admiring them.

With the Prince's elder son about to be married, word is out that the heir to the throne wishes, once the distant day comes, to have his wife crowned beside him as Queen. I find this as unremarkable as if he were to announce that the sun will set this evening: but it is deemed a provocation to all right-thinking people. I am not sure whether this obtuse and offensive view is an accurate reflection of popular sentiment or simply the cynical opportunism of those who purvey it. Either way, it is time to end it once and for all.

The Duchess of Cornwall is the only married woman in the United Kingdom, other than peeresses in their own right or dames, who did not take the rank of her husband on marriage. It was deemed, in 2005, unpalatable for her to become Princess of Wales and, on her husband's succession to the throne, Queen Consort. That the general public felt able to tolerate this insult to the wife of their future sovereign is hardly surprising: only for a minority is it an issue. I am in that minority. I find it rude and insulting in the extreme that the Duchess should be treated as if she were some below-the-salt middle-European courtesan from the late Middle Ages who cannot be deemed worthy of taking her husband's rank. Is public opinion really so spiteful and vindictive, and indeed so unfair? I hope not.

The Duchess clearly played a role in the end of the Prince's first marriage, but by contemporary standards (which we may lament, but that is how things are) she is hardly a scarlet woman. These things happen all the time. What's done is done. Since her marriage, she has worked hard and loyally for the country. More to the point, friends of the Prince say she has been the most wonderful support for him, and he has changed for the better under her influence. She is popular with her stepsons, who would, were they so minded, have more cause to be aggrieved than the rest of us.

The royal wedding will demonstrate the appeal of the monarchy. It is time for the mindless critics of the Prince of Wales and his consort to grow up. It is time to recognise that the Duchess not only has the legal right to be crowned with her husband, but that it would be untenable if she were not. And the process should begin now, by according her the rank, style and title of HRH the Princess of Wales.