After the hard slog – revision, exams, the uneasy hiatus before the results finally come through – comes the reward. This week my son began his undergraduate degree at Trinity College Dublin. It was his long-held ambition, and it is great to see it finally realised. But as a proud Belfastard (as he insists on calling himself), he will be one of just a handful of northerners attending university in the South. Remarkably, fewer than 1 per cent make the decision to cross the Border for their studies, and every year the trickle gets smaller still.

On the campuses, you’re more likely to encounter a student from Shanghai than one from Strabane. Even at Trinity – once a favoured destination for young people from the North, particularly Protestants – the proportion of northern students has fallen to almost 2 per cent, dropping by nearly 23 per cent between 2004-2005 and 2009-2010.

Many northern school-leaver, whatever their perceived tribe, opt to decamp to England, Scotland or Wales: over a period of 10 years, the number of northerners choosing Britain for their degrees has grown by 24 per cent. This, despite the fact that degrees are much cheaper, and no less valuable, just two hours down the road. And you don't have to take a plane to get there.

It’s not as though the situation is much better in reverse: a paltry 4.4 per cent of students in Northern Ireland hail from the Republic.

We may share an island, we may share a language, but when it comes to higher education, it seems the Border may as well be the Berlin Wall. Why should this be so?

Mutual information deficit
The standard reason, frequently given, is a mutual lack of familiarity with each jurisdiction's third-level institutions and application processes. That makes sense from a northern perspective, given the scant visibility that southern universities have in the North's careers fairs and conventions. While canny British universities bombard the North's students – who outperform every other region of the UK at A-level – with prospectuses, there is no love-bombing from the South.

But this state of ho-hum disengagement works both ways. As a 2011 report on the (lack of) cross-Border undergraduate mobility pointed out, while many northern pupils are intensively prepared to deal with the Universities and Colleges Admissions Service (the British university admissions service), there is little or no guidance in how to complete the Central Admissions Office form. Most are left to decipher the complexity of the CAO process – which seems archaic compared to the cheery, user-friendly UCAS approach – on their own.

Points apartheid
Oh, and did I mention the need to do four A-levels, and to score the highest grades in these exams, in order to accumulate sufficient points to gain access to the most sought-after courses? Or that CAO will allocate points only in respect of A-level qualifications taken in the same academic year, thus putting northern students who choose to sit an A-level early at a disadvantage?

And that's before you take into account the prohibitive costs of living in a city such as Dublin or Galway. Perhaps it's not surprising so few young northerners choose to look South for their third-level education. As my son puts it, to get there, you have to really want to go there. Given substantial tuition fees, an alien application process and the additional deterrent of unresolved sectarian tensions, it's even less surprising few southern students think it worthwhile to come North.

Undeniable as these factors are, they don’t quite capture the whole picture. To my mind, the effective absence of third-level cross-pollination is symptomatic of a growing cultural disconnect between North and South which runs beneath the benign amiability of everyday relations between the two. Hostility would be too strong a word. But there is often a sense both parts of the island lead increasingly separate lives, and are not particularly interested in paying the warm, highly focused attention to each other that underpins all successful relationships.

Urgent action is needed, by both governments, to ensure that young people from all parts of this island have the opportunity to learn and talk and laugh alongside one another, encountering the shifting, coalescing points of similarity and difference between them. Space must be set aside, reserved for the purpose. Otherwise that vital conversation may never have a chance to begin.