Australian ad agencies can hear something coming in the air tonight – and it sounds like the end of advertising as they know it.

Cadbury has been paying for airtime to screen its “drumming gorilla” short film on Australian TV for the last few weeks, with Network Ten’s Australian Idol as a key vehicle. First aired in the UK in August 2007, “Gorilla” has been viewed millions of times on YouTube, and many Australians had seen it before it graced local airwaves.

If you’re one of the few who haven’t, the entire piece consists of a guy dressed in a gorilla suit who sits at a drum kit and plays along vigorously to Phil Collins’ 1981 hit In The Air Tonight.

It made me laugh the first time. It’s likeable, engaging and a bit silly, even if you don’t interpret it — as I did in part — as a send-up of Collins’ rather simian drumming style. It’s well shot, and the gorilla suit apparently includes millions of dollars worth of animatronics. And it has won countless awards including Gold at the British Television Advertising Awards, and the Film Grand Prix Lion at the 2008 Cannes Lions.

But there’s one very big problem: it’s NOT an advertisement. That’s what many senior figures in the advertising industry believe, even though they may not be saying so publicly.

Oh sure, there’s a pack shot at the end with a tagline about Cadbury Dairy Milk being “a glass and a half full of joy”. So why isn’t it an ad? Well, fundamentally, because it’s not a planned and strategic piece of marketing communication. At best, you could call it a sponsored piece of entertainment — nothing more than a music clip or a quirky YouTube video “brought to you by Cadbury”. A “publicity stunt”, if you will.

And it’s already leading to situations where the marketing program is driven more by an executional element (the gorilla) than by strategy, as the gorilla becomes the face of Cadbury and guys in gorilla suits start handing out the chocolate bars.

“Gorilla” was created under the auspices of advertising agency Fallon London, and was a major plank of its pitch for the Cadbury account in 2006. In fact, it appears to have been almost entirely the work of hot-shot creative Juan Cabral, who is credited as creative director, art director, copywriter and film/video director.

Not that a drum-playing gorilla is really such an original idea, not even in advertising, as some industry bloggers have suggested. But advertising awards jury gossip has it that Cabral had previously pitched the same idea unsuccessfully to Cinzano in his native Argentina.

Fallon’s planning director Laurence Green told The Independent the agency had “created a branded space in which Cadbury’s can be generous in bringing joy”. In what comes across as a masterpiece of post hoc rationalisation, Green cited “some of the latest advertising thinking” as suggesting that attempts to “impose” traditional components of advertising such as “messages”, “propositions” and “benefits” can actually reduce effectiveness.

Advertising with invisible strategy and unconstrained by messages, propositions or benefits sounds more than a little like the emperor’s new clothes. But this “latest advertising thinking” has some very large Australian clients calling in their agencies and demanding a “Gorilla” of their own.

And the drumming that agency bosses are now hearing in their ears is the sound of their own blood pressure going sky-high as they ponder the implications for the future.

Firstly, if all advertisers need do is “create a branded space” for entertainment, then one centrally-produced short film can run anywhere in the world the locals find a stunt like a drum-playing gorilla entertaining. Subsidiaries of large global consumer goods companies need no longer rely on local agencies to understand consumer behaviour, culture and the competitive environment and shape a strategy around those insights. Just give us the entertainment, thanks, the quirkier the better.

Some Australian agencies have already pitched Gorilla-type ad scripts to clients who asked for them only to have them rejected as under-selling the brand or being too “random”. This suggests it will take a rare combination of brave client, gung ho agency and powerful brand to see such an ad made here.

Worse still, advertisers may start to question whether they need a creative agency at all. Some big brands may decide simply to hire a creative auteur like Juan Cabral, who can (apparently) do it all, or go direct to rock video directors or filmmakers. The latter is what Tourism Australia appears to have done with its new international spots, appointing Baz Luhrmann to direct them before it had even finalised selection of the advertising agency that has to work with what Luhrmann has created.

Given the current economic situation, the prospect of advertisers deciding they don’t need agencies for either strategy or creativity is going down in adland like a gorillagram at a funeral.