Most of us are pumpkins in a modern Cinderella

Once upon a time, during a brief egalitarian period in postwar America, people of different classes did not live in separate worlds. The promise of mobility and prosperity was alive. In 1950, Walt Disney Productions was saved from bankruptcy with its hit Cinderella, which audiences cheered at a time when the future looked bright and it was still possible for the dream of marrying up to come true.

A new Disney Cinderella is a big box-office success today, but how different things look! Cinderella marriages are getting to be as rare as golden coaches. Economist Jeremy Greenwood has found that your chances of marrying outside your income bracket have been dropping since the 1950s because of something called assortative mating, which means that we are increasingly drawn to people in similar circumstances.

Since the 1980s, inequality has grown and mobility has stalled. Today, the rich forge their unions in exclusive social clubs, colleges and gated communities. Unless you have a fortune or a fairy godmother, you're probably out of luck.

Kenneth Branagh's remake seems to offer a sunny romp through the magic kingdom. But a closer look reveals a troubling economic message.

Economists are warning that if we don't do something to stop growing income inequality, we may end up back in a 19th-century world, where hard work won't lift you up the economic ladder because the income from labour is no match for inherited wealth. This is the world of the new Cinderella.

Branagh's version highlights what happens when people are forced to compete for illusive rewards in a harsh economy. Families turn on each other, chances are few and you'd better hope for a magic wand.

Subtle story changes bring the point home. In the original, the father is a widowed gentleman, who remarries and then dies, leaving a jealous stepmother and her mean-girl daughters to torment his only child. But now the father is a merchant, and his death leaves them all in straitened circumstances.