But their days are numbered. They warn that parent protests are not just a waste of time, but a waste of breath too.

The sobering news comes from an American education research firm, Student Monitor, of Ridgewood, New Jersey, which has made some unsettling discoveries.

When students begin at university, 36% per cent already use the plastic. By the time they graduate, the number has swelled to just over half, and by that stage they are using more than just one card.

And something else to bother parents is that those new campus spenders had been using their cards for some years.

“Using credit cards from an early age could set the stage for a lifetime of debt,” admits a Student Monitor spokesman. “But having a credit card during the college years can be a smart move. It’s handy when things go wrong, like if the car breaks down. And if used prudently, it's also an easy way to begin to establish a credit history.”

You could be forgiven for wondering what a credit history might do for a student. But the author of The Ultimate Credit Handbook, Gerri Detweiler, says, “Ironically, credit-card companies are much more willing to give credit to a college student than to a recent graduate who has no credit history at all. And these companies say that college students are better credit risks than the general population.

“Certainly those just entering the work force will find renting an apartment, buying a car, and in some cases even getting a job, much easier with a solid credit history,” she said.

Should fathers leave all credit card decisions to their children? Gerri Detweiler says not necessarily. “It doesn't much matter whether they get a card on their own or you co-sign the card. But remember that with a co-signed card, any outstanding debt, late payments or defaults, will show up on your credit report. For that reason, you'll want to make sure that all the paperwork comes to you.”

Another expert, Robert Manning, author of Credit Card Nation, advises parents to keep an eye on the spending. “After all, emergencies can quickly become redefined,” he says. “It may start off with 'Grandma is sick and I've got to get an airplane ticket,' but then fall to 'It's the last concert of Eminem and I can't miss it.’ Sometimes parents aren't aware that there's a problem with the account until their own credit history is damaged.

“Since kids often aren't educated – at home nor at school - about how to manage money, many college students graduate with a mountain of high-interest debt,” Mr Manning said. “Combined with today's lousy job market and other student-loan debt, that has helped make the under-25 crowd the fastest growing group of bankruptcy filers.”

Gerri Detweiler suggests parents guide their children towards a low spending limit. “You should make sure they understand the importance of a clean credit report,” she said. “It's like a report card that will follow them around for seven years. This is one they really won’t want to fail.”