On exam results days, there’s now something of a social media tradition of those long out of the school system sharing stories of success despite a disappointing set of results. In some cases it’s an honest attempt to reassure those who’ve not hit the high grades that their future is one still full of potential; for Jeremy Clarkson it’s just an annual excuse to show off.

And while the sentiment from many is admirable – of course exams taken in your teens should not define your life – there’s no denying that when 16-year-olds across the UK open their GCSE results tomorrow, much will be determined by what they find inside. Without the right grades, colleges and sixth forms might reject you; the doors to competitive degree courses and universities will either be a little more open or resolutely slammed shut.

Professions such as teaching, social work and medicine require certain GCSE results as a minimum, while research has found that only 16% of employers don’t consider them at all. And then there’s the message that doing badly can so easily send to a child: that they’re not academic, and that the path of further education is not one they should take.

It’s why new analysis from Teach First published today requires urgent attention – the findings are both deeply worrying yet unsurprising at the same time. According to research by the education charity, pupils from disadvantaged backgrounds are almost twice as likely to fail GCSE maths as their wealthier classmates; they’re also only half as likely to hit the highest grades as their more privileged peers. There’s a similar pattern across subjects from English literature to geography and French. And this attainment gap is currently getting worse.

Our education system is letting down poorer children – and in response all we do is scribble “must try harder” on their reports. The myth of the meritocracy has been laid bare.

These findings aren’t just frustrating, they throw the entire validity of our exam system up in the air. To believe in nationally standardised testing as a way of measuring achievement and determining opportunity requires certain principles: that the tests undertaken are identical in complexity, and that everyone sitting them has equal opportunity to do well. Unless you truly believe that there’s a correlation between bank balance and intelligence, it’s clear that our exams aren’t working.

Identifying some solutions is simple: serious investment in primary and secondary education sits top of the list. With school funding cut by 8% since the Tories came to power in 2010 it’s hardly surprising that pupils who require more support inside and out of the classroom are being hit hardest. Support staff and teaching assistants are invaluable in helping those children who’ve missed out on opportunities in their early years to reach their potential – but in an era of cuts, these roles are often some of the first frontline posts to be let go. Any government committed to making our society both fairer and more equal would place reversing these cuts – and increasing spending – at the top of their to-do list.

But until children from all sections of society have an equal chance of success, colleges, universities and even employers should be encouraged – where possible – to take the backgrounds of applicants into account. That could mean anything from adjusting college entry requirements to ignoring GCSE results altogether on job applications.

For those who don’t get top marks across the board tomorrow, it’s right to encourage hope and optimism for what might come next – I haven’t been asked about my GCSE results since my teens and doubt they will ever come up again in an interview. But if we can’t find a way to balance out this GCSE attainment gap, maybe it’s time to question whether it’s the exams – not the pupils – that are failing.

• Michael Segalov is a contributing editor at Huck magazine, a freelance journalist and author