‘YYou can now hand in your documents.” For how many of us does this sentence still give us butterflies in our stomach decades after graduating from high school? Like most people, I have a recurring nightmare before graduating from high school: mine involves organic chemistry and a pile of unopened folders.

This is a cliché, of course, but perhaps a peculiarity of Britain. Our exams are particularly high-stakes. In most other rich countries, except America, grades count for less. French universities are usually happy if you have a high school diploma – the really great universities require extra studying, but there is less emphasis on specific grades. In Germany, you need a high school diploma, and if you don’t get that, you can take a foundation course to make up for it. But here, a single failed grade in a single three-hour sitting can change the course of your life.

To some, this seems harsh – and arbitrary. On graduation day, it has become a tradition to tell school leavers that grades don’t really matter. Every year, Jeremy Clarkson releases a statement about his Cs and two U’s: “And here I am with my own pub.” This year, Richard Branson tweeted: “On one of my last days of school at the age of 15, my headteacher predicted that I would either end up in prison or become a millionaire… So I hope this gives a little encouragement to anyone worrying about their A-level results today!”

This sentiment is reflected in an outburst of reform zeal that followed botched exams during the pandemic: a group of politicians, teachers and businesspeople argued that A-levels should not be as important as they are. They are too stressful, too narrow-minded and too elitist – and in doing so, branded a whole group of young people as failures.

Among those reformers is Peter Hyman, now a senior adviser to Keir Starmer, who once wrote in these pages that a period of teacher assessment is better than the adrenaline-fuelled snapshot of exams. We should assess things like “creativity, collaboration… and communication”, he says, to get a “holistic picture” of each child. This is all well-meaning stuff: exams are far from perfect. But the celebs and the reformers are wrong. A-levels matter. And they should. They are one of the best engines of social mobility we have.

Branson’s tweet will ultimately be more encouraging for students who come from wealthy families. Exams are less important when parents are rich. Branson could afford to drop out of school: his father was a lawyer, his grandfather a High Court judge. Clarkson’s parents, meanwhile, were able to send him to Repton. Connections, internships, social standing – private schools and networks can soften the impact of poor grades, and money softens the fall when risky decisions fail. But not everyone has that.

A more ‘holistic’ assessment is a nice idea, but ambiguous and therefore vulnerable to upper-class interference. Oboe lessons, Mandarin, drama classes, work experience with successful friends – rich parents would do anything to help their children look ‘well-rounded’ on their Ucas forms. Private schools and tutors can, of course, improve exam performance, but the effect is smaller. It is easier to cram a child’s curriculum than to help them excel in an exam they have no aptitude for.

Indeed, the exam hall and the marking room are those rare and sacred spaces that not even wealthy parents can invade. Not that they haven’t tried. Toby Young, who got two Bs and a C in his A-levels, was accepted to Oxford after his famous father called on his behalf. The hereditary peer Lord Bethel once tweeted this encouraging message to students: “I messed up my A-levels. That taught me how to struggle through. First, to get a university place. And I haven’t stopped since.” Such struggles, thankfully, no longer work these days. The pandemic, meanwhile, has taught us the problem with teacher evaluation: students who pay fees are hit with higher prices. And the French and German systems may be more relaxed, but they do far less for the bright student from poor backgrounds who wants to prove their talent. Both France and Germany, by the way, lag far behind the UK and US in terms of social mobility.

It is strange, then, that objections to rigorous, externally assessed exams so often come from the left. It is not just Hyman who is now a key figure in education policy. When France tightened university selection criteria in 2018, there were widespread protests and left-wing candidates vowed to reverse the changes.

The left’s arguments against exams seem to me to be similar in tone to those against meritocracy: it is not meritocratic enough and gives its winners the idea that they have earned their luck. (Such an argument was once put forward by Young’s left-wing academic father, Michael Young, in The rise of meritocracy.)

But this is to avoid a brutal fact. If you abolish one kind of hierarchy, another will take its place. And the second is generally about money and class. Any kind of elite tends to be quite inventive when it comes to justifying the natural order – whether they see it as ordained by God, as a law of the universe, or merely as the result of their intellectual worth.

When Cyril Burt laid the foundations for the 11-plus exam in the first half of the last century, he was battling against the idea that the class system reflected natural ability and that intelligence was so rare in the working class as to be a statistical exception. Exam results proved otherwise.

This year, we hear, universities will admit more students on the basis of their predicted grades – rather than their actual results – in the battle for places, as the number of international applicants falls. This is bad news: predicted grades put state school students at a disadvantage. A-levels are important. We should ensure that this continues.

Martha Gill is a columnist at the Observer