Hollywood's most powerful figure is you

There's a touching scene in Robert Altman's film Gosford Park in which the singer Ivor Novello sits down at a grand piano and plays romantic songs. While his fellow guests bicker and play cards, quite indifferent to his talent, the servants of the house gather outside the door to eavesdrop on the music.

And what Altman records here, quite apart from an instructive sensibility gap between upstairs and downstairs, is a shift in power. As the fame industry begins to crank up production, authority is moving from titles of birth to the titles on record covers and movie posters. No man is a hero to his valet, but the stars will be heroes for millions.

And, like any aristocracy, stardom has its order of precedence. According to the latest issue of Hollywood Reporter, for instance, nobody gets to sit down at the Polo Lounge before Tom Cruise, Julia Roberts and Tom Hanks, who have just tied for first position in the publication's annual Star Power Survey, a list of the 100 most bankable names in the movie business.

Julia, Tom and Tom all scored a perfect 100 in a judging system designed to rate their "opening-weekend fire-power" and "ability to secure financing". What this means in practice is that you could attach their names to a used piece of lavatory paper and it would still get the green light to go into production (the only rational explanation, in some cases, for the quality of the scripts).

"Power" here is not used as a euphemism for allure or sex appeal or style. It means what it says – the ability to make things happen your way. And while actors are still some way down the overall pecking order in Hollywood (in Premiere magazine's power list last year, Hanks was the first actor to make an appearance – and then only in position five) their potency is increasing steadily.

For executives who are risk-averse – and, let's face it, who wouldn't be risk-averse when gambling $100m of shareholders' money? – the star offers a kind of insurance policy. While he or she can't absolutely guarantee the box-office success of a movie, they will unquestionably help.

What's more, if worst comes to the worst, you have at least performed the Hollywood equivalence of due diligence. Take a risk that no one else has taken before and you can safely be accused of culpable recklessness. Take the same risk as everybody else and the worst you can be called is unlucky.

The only problem here is that the system is a feedback loop. The reason the risk is so great is because you have to pay so much for Mel Gibson, Jim Carrey and George Clooney (second, third and fourth on the list) in the first place. And since your insurance policy has itself to be indemnified by massive marketing expenditure, the risk gets greater and the competition for the really gilt-edged insurance policies ever more heated.

The tourniquet tightens, squeezing out novelty and imaginative adventure (are you crazy? You want to add some gratuitous risk to the budget?) in favour of brutal expressions of star power. It's spookily candid that two of the biggest forthcoming Hollywood releases should be subtitled Attack of the Clones (Star Wars Episode 2) and Rise of the Machines (Terminator 3).

There is just one consolation – and it lies with people who would never appear on a Hollywood power list, even if it ran to 10,000 places. Because this isn't, let's face it, the kind of power that sledgehammers through your door at three in the morning or hangs you up by your thumbs if you dissent. It's a power that desperately wants you to like it – and you can withdraw your approval with a capricious cruelty that Genghis Khan might envy.

Julia Roberts might be powerful now, but despots of popular taste have been toppled before. Look on Kevin Costner, ye mighty, and despair.

t.sutcliffe@independent.co.uk