Then when the BBC’s Nicholas Witchell gently asked about his wedding to Camilla Parker Bowles this Friday he hissed sotto voce, “Bloody people. I can’t bear that man. I mean he’s so awful, he really is.”

It was perhaps the first time that Charles’s future subjects had witnessed his petulance in full cry. The surly comments not only brought to mind the unflattering portrait of a cosseted prince painted by friends and courtiers of the late Princess Diana, but unpicked much of the remaining positive feeling for his wedding.

All he had to do was be professional and smile for the media, but he was incapable of containing his temper even for those few minutes. It was left to the usually press shy Prince William to save the day as he deftly batted away a question about his love life by saying he was “gagging” to get on the slopes.

What the sorry incident confirmed is that Charles wants to have it both ways. On the one hand using hand-picked journalists to spin favourable stories. On the other displaying a regal disdain for the self-same PR machine. The grumbling photocall further muddies the waters as he prepares for his controversial second marriage.

Charles is of course not the first Prince of Wales to marry twice. He is following an example set by Britain’s most dissolute heir to the throne, the Prince Regent. His secret marriage to Maria Fitzherbert in 1785 was followed by his betrothal to Princess Caroline of Brunswick.

George was blind drunk at the later wedding, collapsed unconscious on the marital bed, and soon returned to his favourite mistress. Then, when he assumed the throne as George IV, he barred an irate Caroline from his coronation.

Courtiers are hoping for a slightly better outcome from this week’s civil ceremony between Charles and Parker Bowles.

And what a difference a second wife makes. Charles’s fairytale first marriage to Lady Diana Spencer marked the culmination of the Windsors’ weakness for sumptuous royal weddings. With its virginal bride, red carpet and sublime liturgy against the backdrop of St Paul’s Cathedral, the ceremony was marketed as a national celebration.

This unwise conjunction of private relationships with public service had been initiated earlier in the century by Charles’s beloved grandmother, the late Queen Mother. Her wedding to the Duke of York (later King George VI) in 1923 eschewed a modest royal chapel for Westminster Abbey and replaced discrete society celebrations with official rejoicing. Designed to lift Britain from its first world war gloom, the union aimed to establish the Windsor dynasty as the nation’s happy family.

Henceforth, royal relationships were official affairs. Public scrutiny was extended from the monarch and heir to the entire brood. The seeds of PR disasters like last week’s were sown. From then forward, we, too, could rejoice in their happiness. But we could also feel cheated by their adultery. And the multiple indiscretions of junior royals during the 1990s served only to expose the terrible reality behind many a magical marriage.

Recent low-key weddings for Prince Edward and Princess Anne have signalled the end for royal marriages as spectacles of public morality. And this week’s bijou register service marks the logical culmination of such downsizing. Where once the Archbishop of Canterbury officiated, we now have “divorced mother-of-two” Clair Williams as the lead registrar.

Despite his curmudgeonely behaviour, few would begrudge the happiness that Charles and Camilla’s marriage should bring the pair — and despite the Klosters setback Clarence House spin doctors are working overtime to accentuate the positives.