He’s nearing retirement after nearly 20 years as a head. It has been a long, rewarding and sometimes frustrating haul and, now he is ready for a rest.

The problem is he can’t leave yet - the governors are finding it impossible to recruit an immediate replacement.

This scenario will become endemic in the nation’s schools unless the teaching profession takes a long, hard look at where the next generation of leaders is coming from.

Why? Because schools are facing a retirement “bulge” some time in the next decade as the post-war “baby boomer” generation of school leaders leaves the profession. It is almost as if we have assumed they will always be there. After all, many of them have been around a long time, with some notching up 20 years service or more at the helm.

But 42 per cent of England’s heads and deputies are now aged over 50, which means we should brace ourselves for a wave of retirements. This grey exodus will create a serious leadership succession problem if we don’t tackle it - and tackle it soon.

We all value good leadership and recognise it as crucial to raising and sustaining school standards. The culture of discontinuity, where acting heads take over the reins while a replacement is found sooner or later, won’t help. We need continuity: a swift baton change from one head to the next rather than a stop-gap.

The problems may be largely down to demography but a crisis is not inevitable. To paraphrase GK Chesterton: “Don’t believe in a fate that falls on us however we act.” In other words, it isn’t beyond our powers to solve the problem. And it isn’t one of those divisive “us and them” issues that is just a problem for those at the top. It is an issue for all teachers and the answer needs to come from the profession.

Heads must start to see the grooming and development of the next generation of school leaders as an integral, rather than a peripheral, part of their role. A head should be proud to say: “Six of my deputies have gone on to headship and two of our heads of department are going to be deputies.”

While some schools are already showing the way by “growing their own” leaders we can draw useful lessons from the commercial world as well. One of the things that strikes me when talking to business leaders is how chief executives in particular see the development of staff to take on a more senior role in the company as a major part of their role.

All of us in education must think how to bring the next generation of school leaders on and how we will make leadership positions more attractive to them.

Governors, current heads and deputies should encourage leadership at all levels. By giving many more people the opportunity to take responsibility we will create a cadre of colleagues both able and and willing to move into senior positions.

We also need individual schools, governors and leaders to be making headship and deputy headship an attractive option. They should be talking about the joys of headship as well as its pains and perils.

What will leaders of the future be like? There is no reason why the leaders of the 21st century should continue to look as they did in the 20th century. What we certainly can say is that they are likely to be younger and many more will be women.

What is also certain is that these future leaders must be identified by current ones who recognise their leadership potential, encourage them, and give them chances to lead.

It is not too late. We have between six and 10 years before the retirement bulge kicks in. This gives us ample time to develop existing young deputies and bring in a new generation of colleagues who will eventually become heads-in-waiting. But we must act now.

As our fictional head and others like him contemplate a restful retirement it would be entirely natural, in a narrow, selfish sort of way, for them to regard the issue of leadership succession as someone else’s problem.

But that sort of approach won’t help the profession to solve the succession problem. This is where individual action - and altruism - will count.

If you are an educator who believes in schools then think about the legacy you will leave behind if you don’t take steps to ensure that all your good work is passed immediately into secure hands. It would be wrong to say that we are about to tumble over a precipice, but we do have a very steep hill to climb. We will tackle this problem - as long we all take responsibility, act together and act now.

Geoff Southworth is director of research at the National College for School Leadership