Thursday is A-level results day – cue for an English summer ritual to match Glastonbury mud and ill-judged fascinator hats at Ascot. There will be front-page pictures of attractive 18-year-olds exhilarated by their grades, tired articles reheating fears that educational standards are falling and ministerial boasts that students numbers are rising despite dark warnings that the new fee regime would cause them to fall.

It is true that a third of English 18-year-olds now apply to university, a proportion that has more than recovered from the dip that followed the introduction of the new fee and loan regime in 2012. It seems win-win. English universities have been spared what would otherwise have been swingeing cuts – and student numbers are still growing.

There is more apparent good news. In 2015, English universities are spending £800m on promoting access for disadvantaged students as the quid pro quo for increasing their fees to £9,000 – a patchwork quilt of scholarships, fee-waivers, induction and remedial courses and building links with communities and schools to appeal to students from poorer backgrounds. It seems to be working. Analysis by the recent final report of the Independent Commission on Fees (which I chaired) shows that over the past five years the proportion of students from disadvantaged homes has risen markedly.

But below the headline good news there are more ominous trends. If 12,000 more students from poorer homes are enrolling at university than five years ago, that hardly compensates for the collapse in part-time student numbers, falling by 152,000 over the same period. The principal cause is fear of debt, a trend that will be accelerated by the ending of maintenance grants in the budget. While part-time numbers are holding up in Scotland, Northern Ireland and Wales, which don’t charge £6,750 for part-time courses, they are plunging in England, which does. Part-time foundation degrees, certificates and diplomas of higher education are people’s second chance, especially for the over-25s, who represent four-fifths of the drop. The number of mature students doing full-time degrees is also falling. Together this represents one of the biggest setbacks to social mobility in modern times.

The notion that Britain’s students are simply shrugging off debts that by 2020 will be approaching £50,000 as universities index fees to inflation, bringing them near to £10,000, is far too optimistic. Today’s 16- to 18-year-olds are beginning to worry as much about debt as their older peers. A ComRes opinion survey commissioned by the Sutton Trust reports that 78% of young people were concerned as potential students about the cost of living, 68% by high tuition fees and 58% by having to repay student loans. They are right. The US is often quoted as the country whose system of student funding most cloesely corresponds to England’s, but because of generous scholarships in private universities and very low fees charged by many state universities, only 70% of US students graduate with debt, which in any case only averages £22,750. In Britain, all students graduate with debt almost twice the US level.

Already in the US there are grave concerns about the social implications. Couples are waiting longer before they marry; the birthrate is falling; home ownership among under-40s is plummeting; and the rate of small business formation by young people is decreasing. As loan default rates rise, the whole exercise threatens to become self-defeating.The consequences in England promise to be more pronounced. Property prices in relation to income are much higher and graduates shouldering student debt are in no position to save up the huge deposit needed to buy a home. Moreover, the fee regime is interacting with a collapse in young people’s real wages – down more than 10% since 2008.

Britain is in the process of creating the most stratified, least socially mobile, cruelly unfair society in its treatment of the young in the advanced world. The over-50s, rejoicing in the untaxed capital gains they enjoy from buying property a generation ago, will help their own kids, but are not asked to help anyone else’s. As in the US, family formation, the birthrate, home ownership and small business startups are all beginning to be affected and parents will work far into old age to try to help their children. All this to ensure that the allegedly malevolent state is shrunk.

Worse, the debt is structured so that the compound interest rate effect of not paying it off early makes it even more onerous, an effect vastly more likely to hit students from disadvantaged homes. Yes, more are getting to university but, with a few exceptions, not the top ones whose degrees are most valued by employers. Students from advantaged neighbourhoods are 10 times more likely to go to a Russell Group university than those from disadvantaged neighbourhoods. So not only do students from poorer homes have parents not rich enough to be able to help them, their earning power will be less. George Osborne’s legacy, ranging from relaxing inheritance tax to allowing parents to leave their pension pot to their kids and eliminating maintenance grants, will be a society in which the rich are better able to help their indebted children, while the disadvantaged will be left as bottom-tier citizens, renting homes while engaged in a lifelong struggle to repay their student debt. Three-quarters will be paying off loans in their 50s.

And as in the US, default rates are rising. The Department for Business, Innovation and Skills now thinks that 45% of the loans for full-time students will never be repaid, along with 65% of loans to part-time students; the taxpayer will pick up the bill. Indeed, the default rate is now so high that the system is nearly as costly as the low-fee regime it replaced. Meanwhile, universities are finding that more students want to do degrees more likely to deliver high salaries; little by little, they are being transformed from centres of rounded academic teaching and research excellence across the gamut of subjects to high-class employment agencies.

Is any of this what we want as a society? Is it so important that the state consumes only 35.5% of GDP rather than, say, 37% that we are prepared to sacrifice social mobility, entrench class, lower home ownership, enslave a generation to debt and diminish the idea of the university? At the very least, average debt levels should be no higher than those in the US, with many more concessions for those from disadvantaged backgrounds. This is too big a cause to be marginalised as that of the “left”. It is everyone’s – and time mainstream politicians spoke up.

Will Hutton is principal of Hertford College, Oxford