I'm writing this in mid-April; in two weeks time I am bidden by the Master of the Household to a gathering, a sort of knees-up with flunkies, I suppose, at Windsor Castle. It's the Queen's Jubilee party for the media. I wouldn't miss it for the world. I have no idea at all why I was invited. I'm quite sure it's not because the Queen reads my paper, the Guardian, though at one time we had in Richard Baerlin an outstanding horserace tipster. I'm certain that no panel of eminent persons went through the tens of thousands of people who work for the British media and picked out my name for long and distinguished service. Most likely it's because I'm on somebody's Rolodex or in their Filofax, and I think I know whose – a diplomat I knew and liked in the US, and who later had a spell at Buckingham Palace. I must have been on some list of his, and it's survived his departure. But of course I'm going. Who wouldn't? I have no great wish to bow to Her Majesty, and would be disposed not to if asked. I don't expect to hobnob with her; we seem to have no interests in common, and although we know many of the same politicians, and possibly share the same view of them, I doubt if she would wish to join in a little bantering mockery. But the splendour, the history! The armies of servitors and courtiers, the little details to take home like souvenirs for your family and friends. Will it be nice food, or horrid bits of cheese and cocktail onions on sticks? Will there be real champagne, or will the waiters hide bottles of Cava behind starched napkins? Who will the Queen talk to? If Prince Philip makes one of his offensive little jokes, will the victim offer a glassy smile in reply or be drunk enough to tell him to get lost? I shall enjoy every moment.

But a lot of people wouldn't share my anticipation. There are plenty who would want the Palace stiffy (and it is thick enough to stop a small calibre bullet) only so they could reply with a few well-chosen republican sentiments, vigorously expressed. Some people find the very notion of the Royal Family painfully unpleasant. You only had to read the Guardian letters page in the days after the Queen Mother died to see just how much. It goes beyond a general sense that it is demeaning for free people to live in a monarchy, or that the Queen exists as the peak of an unjust and restrictive class system, or even that they cost us too much. It's a visceral, gut hatred, an emotional loathing as intense as the fear and resentment felt by a French or Russian peasant before their revolutions – only without, and this is important, the poverty and tyranny that the French and the Russians had to put up with.

Many Guardian letter writers couldn't even accept that the Queen Mum was a powerful emotional symbol for many people who had lived through the Second World War and the battles that were fought by (as the Americans put it) our greatest generation. A few days after the Queen Mother died, I quoted with approval a speech by Oona King, a young black woman who is MP for Hackney, where the Queen and sometimes the then King used to visit after, and sometimes during, bombing raids. Ms King is fairly left-wing, at least in New Labour terms, and I thought her speech was generous in reaching out to constituents who might live in the same place, but whose life-time experience and outlook might be different from hers. But I got several angry letters – some pointing out, reasonably enough, that there had been some booing and jeering of the Royals at the time, others furiously saying that a typical ARP warden had shown far more courage far longer than any king or queen. Well yes, but what counted was that they had arrived as the representatives of the nation as a whole. The message was not: "Rich people who like to go shooting and have all the food they can eat support you" but "from Land's End to John o'Groats, everyone is with you". That was the message, that's what the East Enders were responding to, and that's why Oona King was right to recall it. In any case, I'd rather that than George W Bush spending much of September 11 hiding in a field in Nebraska. Clearly Bush, as Commander in Chief, was being protected by the military. But there are times when a natural leader sees the importance of symbolism and lets it override personal safety. Thanks, Ma'am.

The apex of conservatism?

Most analyses of British failures made by the Left or Centre-left offer at some point the suggestion that our national incompetence – trains, the NHS, wobbly bridges – is indirectly the fault of the Royals, or at least that their removal is essential if we are ever to reform. Will Hutton, for example, makes many interesting points in his 1996 book The State We're In, but can't resist the usual side-swipe. He blames the Royals for, indirectly, keeping the Tory party in power: "At the end of the 20th Century the Conservative nexus retains its tribal grip on the imaginations and institutions of the English." (For some reason it is usually taken as a given that Scots and Welsh people already all reject the monarchy even while they stubbornly refuse to make the break for freedom.) "The apex of this system," Hutton continues, "remains the Court, where the aristocracy continues to serve the Queen in a series of functions whose ridiculous Ruritanian names mask the political and social importance of the informal Conservative networks at whose centre these positions place them." He points out one or two examples, such as Lady Susan Hussey, a Woman of the Bedchamber, who is the sister of the Conservative cabinet minister William Waldegrave.

A year after Hutton's book was published, the old Conservative nexus got a kick in the goolies from which it has yet to recover. And amazingly, the brother of the Woman of the Bedchamber, failed to hold his seat along with five other cabinet members! The voters of Bristol were unmoved by his Ruritanian grandeur. Nexus, schmexus. What those writers who see the monarchy as one great conspiracy fail to notice is that some conspiracies, like the Gunpowder Plot, are just no bloody good.

And why does nobody compare our constitutional monarchy with the others? No one ever argues that the Japanese Imperial Family, an institution which at home commands far more reverence than ours, which survived the most humiliating military defeat of the last century, and whose agonisingly strict formality makes ours look like the Beverly Hillbillies, somehow stopped the Japanese from selling cars, cameras and electronics around the world. The Benelux countries, most of Scandinavia, and now Spain are doing pretty well too. (Spain was technically a Republic under Franco. That didn't help much.) Canada and Australia have monarchical systems, and they seem to be struggling by. Until the latest enlargement, half of all EU countries were monarchies, including Luxembourg, which may be a dreary little statelet but still manages to be the richest per capita nation in the world.

The fact is that the system is a reasonably good one, and if it doesn't work, it's our fault, and not that of the people who, by accident of birth, are stuck at the top of it. You don't blame the fairy if the Christmas tree collapses. The arguments in favour of a constitutional monarchy are simple, well-rehearsed, and in my view adequate. Since all the great institutions of the state – the executive, the legislature, the civil service, the judiciary, the military, and in our case the established Church, not to mention the Boy Scouts – all owe their loyalty to an essentially powerless figurehead, then they don't owe their loyalty to each other. (Small point, but when the Falklands were re-captured, the CO said on that crackly radio: "The Union flag now flies over Port Stanley. God save the Queen." He did not say, "thank you Mrs Thatcher." Nor did he say, "this is a great victory for the Conservative nexus".)

Okay, it doesn't always work as it should. Look at what happens when a government – to pluck an example at random, the present one – tries to change that, to divert the flow of power not to a symbolic centre, but back to itself. The Blair attempt to subvert the civil service, to make its primary loyalty to the government of the day rather than to the Queen and hence the nation, is a crime for which we will pay for decades to come. (And it will be worse than Jo Moore's silly e-mails about burying bad news. In the end, what New Labour wants is to make the civil service work to its agenda, which is the re-election of New Labour. This is the real bad news they would like to bury, and I write as someone who would find it harder to vote Tory than fry my own hands in batter.)

What's the alternative?

The other big question is, who instead? Suppose we don't go for an American or French system, in which a president engages in an ongoing struggle with the legislature (fruitful in many cases, hopeless in others. Look at health care reform in the US. The voters wanted it, which is why they elected Clinton in 1992. They didn't get it because their legislators needed the doctors' and the insurers' money too much. I don't suppose having a Queen would have helped, but not having one didn't exactly solve the problem. You could argue too that the US system was built in the 18th century as an elected monarchy; George Washington was even begged by his generals to declare himself king.)

We could have the German system (superannuated old politician acts as president) or the Irish system (superannuated old politician acts as president, relieved only by Mary Robinson). Or perhaps we should choose someone outside the system who commands universal respect. Stephen Hawking? Jeremy Paxman? Vera Lynn? Bobby Charlton? To ask the question invites derision or embarrassment.

But the Queen does, to some extent, hold the prime minister to account. Every week they're both in the country he has to go to Buck House and give an account of himself. And it's not to some la-di-da racing fan who wants to get it over with and have another gin. She knows a lot and she's encountered many prime ministers. God knows, Blair goes his own sweet way, but I sometimes dread to think what might happen if he didn't have to face that stern old woman who's read all the boxes, who can't be offered promotion and who doesn't owe him a thing. I suspect it wouldn't work like that if we had Geoffrey Howe or even Mo Mowlam sitting there. Even if we had elected them. Especially if we had elected them. If there's one thing a politician knows, it's how to get round another politician.

I think the most important thing is that, since the system ain't broke – however much some people think it is – let's not even try to fix it. We do not have a good record of fixing things. Politicians have been seriously trying to reform the House of Lords since 1906 and to replace it with something fairer and more effective. They have failed. (The Parliament Acts which did sharply reduce the peers' powers were passed thanks to, whoops, the common sense of Edward VII and George V.) Every attempt at reform has crashed down simply because in a free but peaceful society nobody can ever agree on constitutional reform. That's why you need a revolution (France, US, Russia) or a military defeat (Germany, Japan) that allows someone else to impose one on the smoking ruins. Believe me, if we abolished our constitutional monarchy the row that followed would never end. Nor has it with the Lords. Right now our elected prime minister, having got rid of all but a hundred hereditaries, proposes to form a new House in which 80 per cent of members will be chosen – by people chosen by him. Why does this not make a democrat's heart throb with pride?

The make-up of the present family is, of course, a different matter. We could wish for other people. I sometimes suspect that if the Royals lived on a sink estate, social workers would have a case conference about them weekly. Of course, until Rupert Murdoch arrived we didn't know much about them. They were symbols and that was that. To ask about their private lives would have been as absurd and beside the point as an American inquiring what the Statue of Liberty got up to at night. (Actually they didn't even demand to know what FDR, JFK and even Eisenhower were doing at night. Now, like us, they get to read analysis of semen stains.) The Royals have become just another bunch of celebs, and apparently their intimate lives are as much our business as Kate Winslet's new lover or whether a Pop Idol is gay.

To sum up: the system isn't perfect, and we sure wouldn't have started from here. But it does work, it has some advantages, and you can be sure that any replacement – if we could ever work one out – would be worse. In the meantime, if the editors let me, I'll report back to you on the party.