What an idiot! What an abject fool! As Prince Harry swiftly admitted, his German army uniform, complete with swastika arm-band, was "a poor choice of costume". It was, in fact, about the poorest choice he could have made. It was misguided and crass. It took no account of his position as third in line to the throne; it was a symbol of thuggish bravado calculated to raise a cheap laugh. It was a joke in execrable taste that also misfired the moment the photographic evidence became public.

What an idiot! What an abject fool! As Prince Harry swiftly admitted, his German army uniform, complete with swastika arm-band, was "a poor choice of costume". It was, in fact, about the poorest choice he could have made. It was misguided and crass. It took no account of his position as third in line to the throne; it was a symbol of thuggish bravado calculated to raise a cheap laugh. It was a joke in execrable taste that also misfired the moment the photographic evidence became public.

The question is: was it more than this and how shocked should we be - if at all? First, the theme of this fancy-dress party showed the sort of society that the princes and their contemporaries move in - and not to its, or to their, advantage. Here were young people of privilege and considerable wealth invited to dress up as "colonials and natives". All right, so it was a night out with friends, a bit of fun, intended to be satirical, even. But the theme alone betrays a view of the world so outdated as to be hopelessly out of touch. It is to Prince William's credit that he arrived in a black patterned leotard accessorised with paws and a leopard's tail - an interpretation of the theme that was almost witty, and gloriously apolitical.

The same, alas, cannot be said of the younger prince's Nazi armband. Any symbol more likely to cause offence among broad swathes of opinion in this country is hard to imagine. And, yes, it makes a difference that he is a prince. This was a hugely insensitive form of fancy dress for a prince of the realm to adopt, even for a few hours. Not only did millions of Britons die fighting to defeat the Third Reich and the ideology that sustained it, but we are barely a week away from Holocaust Day and the 60th anniversary of the discovery of the Auschwitz death camp. Members of the Royal Family, the Queen included, will be helping to commemorate this bitterest of anniversaries.

At such a time, Prince Harry's costume strikes an especially discordant note and one that will do Britain no favours at all abroad, especially in those many European countries which suffered under Nazi occupation. Can one conceive of an heir to any European throne, a member of any leading foreign political family, even the rebellious daughters of George Bush, socialising with a swastika on their arm?

And yet, and yet ... There is a malign tendency in this country to take offence at almost anything. We have long grown used to seeing Nazis depicted as figures of popular ridicule or fun. From Fawlty Towers to the musical, The Producers, which is now playing to packed houses in London, the whole Nazi shebang - swastika, goose-stepping, rasping orders, straight-armed salutes - raises an easy laugh. Like it or not, laughter is a way in which the British have long belittled their historical enemy and defused the danger of Nazism.

Again, like it or not - and the same people will not - these humorous depictions are very different from the adulation of Nazism that ebbs and flows among adherents of the far right - in this country and many others. Were there the slightest suspicion that Prince Harry was wearing his swastika in anything other than Basil Fawlty or satirical mode, we would deplore it unconditionally and have no hesitation in questioning his suitability either to enter the army or inherit the throne. Whatever the younger prince's swastika meant, we are confident that it did not signify any sympathy for Nazism.

Most likely, what it meant was foolish, decadent fun, laced with a large dose of ignorance and insensitivity. For a newspaper such as ours, with deep misgivings about the monarchy, we find it hard to be either surprised or shocked by Prince Harry's behaviour. It is yet more evidence of how detached the next generation of royals remains from the lives of their subjects and how outdated a constitutional system we have. The bottom line is that this was a young man on a night out who should have known better and could have done with some decent advice. In the event that his armband helps to sap support for the monarchy, it may even have done some good.