Poor Prince Harry - with the sort of upbringing the sons of royalty receive, he might be said to have suffered child abuse. And he is only 20.

That said, when Henry VIII was 20 he was doing his share of hunting, boozing and wenching to be sure; but he was also studying theology to such depth that the Pope awarded him the title Defender of the Faith. This is the "Fid Def" still found on British coins, but which will feature on them no longer if we scrap the pound.

And, given our totalitarian Government's obsession with banning things, hunting will soon no longer be a pastime available to the Prince. The only theology we are left with is that of Rowan Williams. That just leaves 24-hour boozing.

Still, it was pretty daft even for a royal oik like Harry to go dressed up as a Nazi. But the reaction to it has been silly and enough to have brought that saccharine smile to the face of Princess Diana herself.

But there are questions to be asked. Is it deemed offensive for anyone to dress up as a Nazi or for Nazis to be pictured in any form - or does the disapproval extend only to members of the Royal Family? The TV screen is filled with images of Nazis, what with all these programmes about the Third Reich and the Second World War.

Besides, to dress up as a Nazi doesn't mean you are a supporter of National Socialism any more than togging up as the demon king means you're a devil-worshipper. It was a fancy dress party after all and meant to be a charade, a mockery. That Nazi costume of Harry's could well be seen as a way of making fun of Hitler's gang - as in that episode of Dad's Army where one of the cast dresses up in German uniform.

You can be sure of one thing: if Harry had worn the insignia of the hammer and sickle - the emblem of the USSR - no-one would have raised any objection. And yet Stalin exterminated many more millions of innocent people than were ever murdered by Hitler.

But that doesn't count. The evils of the Soviet Union in general and of Stalin in particular are always glossed over by the left wing establishment. For decades, the left praised the USSR to the very heavens even while millions were being tortured and killed in the gulag.

Lunatic veggies such as the overblown George Bernard Shaw said that Stalinist Russia was the nearest thing to paradise on earth. The Blair Cabinet is full of unreconstructed lefties and former CND supporters, anti-Vietnam marchers, Greenham fellow-Commoners and other sentimentalists who could always find a kind word for communist countries while scorning patriotism for Britain.

No, the only taboo is to be a Nazi. Harry might have gone dressed up as Stalin, Chairman Mau, Pol Pot or even a British abortionist and there would have been no outcry. But to pretend to be a Nazi is unforgivable. Why should all those other, greater, mass murderers escape condemnation? Because Nazism is held to have been right wing. But it wasn't. NAZI, remember, stood for the National Socialist Workers Party. Hitler was the 20th century's founder of the fascist left - the sort of party that liked banning things. Ring any bells, does it?

* Peter Mullen is Rector of St Michael's, Cornhill, in the City of London, and Chaplain to the Stock Exchange.