Even the servants can't follow the royal script

Even for the more dedicated royal-watchers, the "revelations" during and since the trial of Paul Burrell, the Princess of Wales's former butler, may seem of the utmost triviality. An unhappily married woman has lovers; one gives her a signet ring; her father-in-law writes brusque letters; a man with a broken arm needs someone to hold the bottle while he gives a urine sample, and is too embarrassed to let a strange nurse do it. These storylines seem too predictable, and the plot too tired, for any soap opera, let alone one as expensive as this.

The case is nevertheless important because it illustrates two things. First, the monarchy looks foolish, anachronistic and faintly sinister as soon as circumstances force it to move from ceremony and fantasy to the realities of modern life. It can do hatches, matches, dispatches and anniversaries with ease and grace. It rises in public esteem when it has a 101-year-old to bury, a jubilee to celebrate or a romantic wedding to put on. Between times, it will increasingly arouse a mixture of public derision and resentment because so many of the trappings simply don't work any more. Just as Diana could not play the role of a fairy-tale princess living in gilded palaces, just as the Prince of Wales cannot keep up the pretence of being a man with no opinions, so even as quaint and naturally deferential a figure as Mr Burrell cannot behave as a servant surely would have done 50 years ago. He may have remained moderately discreet for a period (though only, apparently, about his curious meeting with the Queen), but he was not in the end prepared to go to prison for his monarch, let alone to die for her. He would not even forgo the cheque from a tabloid editor, the receipt of which now seems to be the inalienable right of every defendant acquitted in a high-profile trial.

The second and more important point is that the case highlights how the law and the British constitution are based on nonsense. It was in the Queen's name that Mr Burrell was prosecuted, just as it is in the Queen's name that the prime minister appoints judges, sets up quangos, signs international treaties, runs the secret services and, above all, goes to war. Whether this means that Her Majesty can be summoned to give evidence in one of her own courts (and can send herself to prison for perjury if she fails to tell the whole truth) is a conundrum that only Lord St John of Fawsley can resolve: other countries have written constitutions, we have Lord St John, himself a figure that seems to have walked out of a Gilbert and Sullivan opera.

The problem with the royal prerogative, therefore, is not only that it is undemocratic (and no less so when it is exercised by a prime minister) but that it is imprecise. The instinct of modern bureaucrats and politicians is to codify everything from teachers' duties to the length of bananas. Yet the precise rights and duties of the sovereign, and her status under the law, remain inscrutable - a matter now being examined by a Fabian Society commission due to report next year.

Tony Blair, otherwise so proud of his reforming constitutional zeal, otherwise so anxious to embrace modernity, remains on this subject quite resistant to change so that, even in the Burrell case, he merely repeats his complete confidence in the Queen's infallibility.

No wonder. If anachronistic powers were removed from the Queen, where else would they go? If they went formally to the prime minister (making de jure what is now de facto), the power of Downing Street would be too nakedly exposed and the renewed taunts of "President Blair" too much to bear. But heaven forfend that they should go to parliament, turning Britain at last into a true democracy.

Why IDS needs Tory disunity

And so to the nation's other long-running soap opera: the various people, some of them bald-headed, fighting over the toothcomb that the Conservative Party has become. And to the question: why have the Tories, almost alone among right-wing parties in western democracies, found it impossible to recover from the social democratic tide of the late 1990s? New Labour's performance - combining economic success with skilful media control and carefully trimmed policies - provides an inadequate explanation. Centre-right parties in, for example, the US and the Netherlands faced much the same mixture but are now back in power.

The Conservatives' real problem is more deep-rooted: it has become extremely difficult for any opposition party in Britain to present itself as a credible alternative government. This is very largely the Tories' own doing, and serve them right, but the implications should concern us all. The emasculation of local government, the growth of government-appointed quangos, the executive's domination of parliament, the centralisation of the media, all combine to make opposition politicians seem irrelevant. No Tory or Liberal Democrat can acquire, in voters' eyes, the weight that comes from being a prominent senator or state governor in the US, or a city mayor in continental Europe. Only by fighting an organised group within their own party - the Militant Tendency or the trade unions, say - and by publicly and dramatically imposing their will on such internal foes can opposition politicians in Britain gain any kind of public stature.

It is possible that Iain Duncan Smith dimly understands this, and that it explains his defiant statement against "the enemy within" on Tuesday. His problem is that he faces no organised, entrenched factions, only a variety of squabbling, opportunistic individuals. And "unite or die" is the wrong message: if he is to prove that he can perform as a heavyweight politician, unity is the last thing he needs.