What would Henry Higgins say?

Emma Thomspn has derided Audrey Hepburn's portrayal of Eliza Doolittle as she prepares for a new version of My Fair Lady.

Emma Thompson's criticism of Audrey Hepburn has caused uproar.

Here's one way of generating publicity for your new screenplay. Rather than excitably telling everyone of the great storyline or the hopes you have for the director, hit the headlines by casting aspersions on the much-loved original. Better still, tell a widely read magazine that the iconic lead wasn't actually all that good. It's the kind of opprobrium you'd probably expect from a caustic film-maker such as Quentin Tarantino. But when Emma Thompson, for many the epitome of the demure Englishwoman, told The Hollywood Reporter and Variety last week that she found Audrey Hepburn "fantastically twee" in My Fair Lady, it caused shockwaves. The screenwriter Frederic Raphael, who worked with Hepburn on 1967's Two For The Road, told The Daily Telegraph: "Audrey was never an actress in Miss Thompson's acid-drop class. She was a lot more than that. You came, you saw her and you were conquered."

Raphael felt the need to respond, perhaps, because Thompson didn't stop at calling Hepburn fantastically twee. "She can't sing and she can't really act, I'm afraid," she continued. "I'm sure she was a delightful woman - and perhaps if I had known her I would have enjoyed her acting more, but I don't and I didn't, so that's all there is to it, really." Thompson went on to suggest her version of My Fair Lady will give the story a feminist makeover. But however interesting that, or the speculation that Carey Mulligan will play Eliza Doolittle, might have been, it was lost in the Hepburn storm. Because of the other iconic films she starred in - Roman Holiday, Breakfast At Tiffany's, Wait Until Dark - Hepburn is an almost untouchable figure.

She belongs, then, to a cabal of "classic" actors and filmmakers who, it seems, are above criticism. Marilyn Monroe (who Hepburn replaced in Breakfast At Tiffany's) was, let's be honest, not a great actress. And knocking Irving Berlin for his unbelievably sentimental musical White Christmas is akin to saying Santa Claus doesn't exist in some quarters. But that film had barely any plot beyond Bing Crosby and Danny Kaye wanting to cheer up their former wartime general by putting on a show. It's not even an original: the song White Christmas first appeared in the 1942 musical Holiday Inn, of which this is a remake so brazen, they even used the same set.

Of course, it's easy to mock old films, simply because they're often products of a different, unfamiliar time. But there are paragons of the modern era too, and they're called cult films. Of these, Kevin Smith's Clerks must surely go down as one of the most continually overrated movies of all time. Two annoying dudes in a video store talking about their nerdy lives and rating Star Wars movies might have had some charm in 1994, but it's not particularly impressive now. Still, suggest that it was successful simply because it pressed lots of mid-1990s cultural buttons, and cineastes will look at you in horror. And somehow, the cult of Clerks has led to sequels, comics and an animated series.

In criticising Hepburn, Thompson was actually vocalising a feeling we all have: there is nothing more annoying than being told what to like. But it's not exclusive to film. In music, if you miss the point about a cultural "hero", you might as well admit you're tone deaf. James Brown may have been venerated as the godfather of soul, but actually, can you really name more than four of his songs? The rest are interminable funk workouts. While we're talking lengthy jams with no apparent purpose, The Rolling Stones are more than capable of giving James Brown a run for his money, most memorably on the 1965 album Aftermath. It might have featured Under My Thumb and Out Of Time, two classics of the mid 1960s. But there's also the excruciating, 11-minute-long Goin' Home. Mention such patchiness - as I once mistakenly did at a Rolling Stones gig - and whole armies of music police descend to put you right.

So it's actually something of a relief that Emma Thompson has spoken the unspeakable - that our cultural icons might not have the consistent body of work everyone thinks they have. It gives hope to everyone who thinks it's a guilty secret that, actually, they can only get halfway through a Beatles record, and don't really understand the fuss about Lost In Translation. But woe betide Thompson if her new version of My Fair Lady isn't up to scratch. A whole army of Hepburn-lovers must surely be just waiting to shoot her down.