In 1948, the embattled Egyptian King Farouk said that soon only five ruling royals would be left: the kings of hearts, clubs, diamonds, and spades, and the English monarch. It now looks as if he was off by one. The monarchy will not, however, drown in a wave of republican sentiment; nor will it be discarded because it fails. The crisis, when it comes, will be provoked by the unwillingness of the royal family to carry on with the job.

In theory, royals should symbolize collective national purpose—if and where such a thing exists—and embody common values. That was the role for which Queen Elizabeth ii’s brood seemed perfectly suited when they were young. Courtiers, counsellors, and the media cast them as an ideal of bourgeois gentility. Then history took over. The royals turned out to be all too representative of their times—more like a sitcom household or a soap-opera dynasty than a model family: dim or daft, undisciplined, self-indulgent, driven by petty enmities, and animated only by infidelities.

Their pomp and glitter now look tawdry and overpriced—a gold tooth in a mouth full of decay. Charles, the prince of Wales, who has done so much for society and the environment, could have harnessed the goodwill of his people. Instead, he has turned his tragedy into farce. The latest of his bumbles was to book a shabby civil wedding, which can be represented as legal only by appealing, ludicrously, to the European Convention on Human Rights. We have thus discovered the world’s smallest and richest disadvantaged minority.

In short, the royals have done an abominable job in a role they chose for themselves. By any normal criteria of employment, they ought to be sacked. Lamely and risibly, however, they can still do the day job—which is to stay mum, sign legislation, and...