The number of sixth formers is due to rise significantly in the next few years.

The number of children needing school and college places changes all the time. It ebbs and flows in waves, and local and national governments has to keep an eye on trends and reduce or increase the stock in response to them.

In recent years, we have seen a significant rise in the population of young people. First, this wave of additional children reached the shores of the primary sector and we struggled to find enough school places for everyone.

We squeezed more pupils into the reception classes, we built temporary classrooms on playing fields, we added an extra class where a room could be found, local authorities opened up bidding for new schools and we opened free schools.

'More children means more teachers'

Then the wave rolled on and reached secondary schools, putting pressure on their capacity and the consequent greater demand for school places has presented the same problems and led to similar solutions.

And, of course, it is not just classrooms – and playing fields, toilets, cafeterias and social spaces – that are under pressure.

More children means more teachers, and many schools are desperately struggling with recruitment and retention. The teacher shortage is a priority.

But at the very time when we need more teachers to educate more children, our 16 to 24 age range (the pipeline for the next generation of teachers) has low numbers – the population wave had receded 20 years ago – and this is one of the reasons why teacher supply is falling behind demand.

What makes an excellent sixth form education?

It also means that there will be fewer skilled workers joining the workforce at a time when we are going to need more (post-Brexit). This is, to some extent, what is driving the focus on T levels.

The wave carrying current population bulge will soon be reaching the sixth form phase and we need to be ready to address the inevitable pressure on capacity and the anticipated shortage of good places for 16- to 18-year-olds.

So, what should we do?

Before hurtling into piecemeal and inappropriate solutions, we need to understand what makes an excellent sixth form education, and then how we can make the best model available as widely as possible.

Introduction of T levels

If we know what works, we can properly plan a high-quality and affordable model for the growing number of young people.

Most 16- to 18-year-old level 3 students choose a sixth form pathway, with some 10 per cent of them opting instead for a technical pathway – though this is set to grow with the introduction of T levels from 2020.

Those who choose an academic pathway (including applied generals like BTECs) mostly choose a school sixth form or a sixth form college.

So, which of these provides the most effective preparation for university and the world of work, and which are the most cost-efficient? The answers to these two questions should inform the growth strategy.

'Time to evaluate what we want'

There is no one-size-fits-all answer. School sixth forms, even small and financially unviable ones, provide essential services in some rural communities, and some young people are better suited to the small and familiar environment of a school sixth form.

Sixth form colleges benefit from economies of scale and can offer a broader choice of subjects, their teachers are specialists, focussing as they do on just sixth form teaching, and they can offer a wider range of wraparound experiences that are essential to a good sixth form education.

Now is the time to evaluate what we want the sixth form landscape to look like in years to come. The capital investment required in building up the additional places, and the critical importance of ensuring our young people get the very best education, make this a priority, and we now have a golden opportunity to get it right for the uncertain world we are entering.

Bill Watkin is the chief executive of the Sixth Form Colleges Association