An already apparent shortage of good headship candidates looks likely to become a crisis - and within the school lifetimes of children now in primary classes.
The problem lies in the double whammy of an ageing community of heads combined with a declining pool of up-and-coming classroom teachers.
Something, clearly, has to be done. Three recent reports from the National College for School Leadership offer different solutions, from how to spot and nurture new talent to keeping those already in post for longer.
The problem is highlighted in Growing tomorrow's school leaders: the challenge, by Frank Hartle and Katherine Thomas of the Hay Group. It says that half of teachers are over 45, and less than one in five is under 30.
As 45 per cent of all heads, deputies and assistant heads are now over 50 we have in the authors' phrase "a demographic timebomb".
"We have between six and 10 years before the retirement bulge kicks in," they warn.
They call for action from schools, local education authorities, government and the school leadership college to bring on potential leaders: the "grow your own" solution.
Geoff Southworth, NCSL's director of research, said: "In the past we relied on an informal, passive approach to recruitment and retention. That won't serve us well in the future. We'll need a much more systematic and active approach."
The impending crisis is not confined to education, and the report urges schools to follow the example of organisations which have already adopted positive leadership development strategies.
The key is to look beyond fixed hierarchical structures and be freer about encouraging people to take on leadership roles within which they can hone their skills.
The report gives a striking example of this in practice, from the head of a technology college.
"I have an open policy towards my senior management team. Staff can apply to join with a simple brief outline of their reasons. We do not put a limit on the numbers or the time someone can serve."
That kind of approach makes a range of assumptions, for instance that the school is prepared not only to take risks, but to be flexible about its hierarchies. Once, you learned your trade at each level from post of responsibility to deputy head. Now, the preferred pattern is of "distributed leadership".
"Research has shown that learning is improved most when leadership is located closest to the classroom and distributed throughout the school," claims the Hartle and Thomas report. "The key players here are heads of department in secondary schools and subject and key stage leaders in primary schools."
The catch is that putting all of this in place - distributed leadership, a broad range of routes to the top, a risk-taking culture - is a big leadership challenge, and it is probably too much to expect individual schools to tackle it alone.
"Leadership talent development must be a local, regional and national priority," the report concludes. "Schools need to work with other schools, with LEAs and with national bodies such as the NCSL, the General Teaching Council, the Teacher Training Agency and teacher-training providers."
Nurturing promising individuals as leaders is one thing. How reliably, though, can you spot them in the first place? Dr Dianne Barker, head of Violet Lane infant school in Burton-on-Trent had a belief - which many heads will recognise - that she could spot potential headship in teachers of two or three years' experience. In her NCSL project, Lost quality in emergent leadership?, six heads pooled their experience, together picked out seven teachers - relatively inexperienced but judged to be headed for the top - and gave them new challenges with new people. For example, they led staff meetings or in-service training in other schools where they weren't known. Dr Barker calls it "putting them in the cold comfort zone - because I don't think there's enough preparation for the shock of headship".
Though a limited experiment, it points to yet another way by which future leaders might be spotted and nurtured rather than lost.
As well as nurturing new talent, though, we could try harder to keep the heads we already have. That's where work by Alan Flintham, head of Quarrydale school in Nottinghamshire, comes in. His research for the NCSL is reported as When reservoirs run dry: why some headteachers leave headship early. It is an absorbing account that will strike chords with every experienced head or teacher who reads it.
Mr Flintham divides his departing heads into three groups: "striders", who move on in a planned way to another challenge; "strollers", who retreat, but in a controlled way; and "stumblers", who leave defeated, perhaps into ill-health retirement.
What is really interesting about this categorisation (and the boundaries are not always clear cut) is that it is not so much the challenges that differ as the responses of the heads. Being a "strider", for example, does not necessarily mean being more effective. Flintham quotes one successful head discussing a long, drawn-out intractable problem.
"I admitted that I couldn't deal with it to the chair of governors, instead of trying to con my way through it as a superman. As long as I could articulate my weakness to someone it was OK."
This ability to "compartmentalise" - to admit an imperfection and put it into an emotional box, maybe with someone's help - is important. By contrast, a head aged 48 who left the job after a crisis in staff relationships, said: "My self-belief was undermined. I felt a good head would have solved this, and I had no one to convince me otherwise."
Flintham's stories are vivid, and sometimes moving when you contemplate the personal and family repercussions of a departure that one head describes as "like a bereavement".
The positive side to his work, though, is that it is possible to distil from it some of the ways by which stumbling, strolling - even striding - might be averted or at least postponed. Foremost among these, perhaps, is the need for headteachers to have someone to talk to. Yes, there are chairs of governors, advisers, the head down the road, but what is really needed, according to Flintham, is for this to be made into a formal entitlement: "funded and legitimised reflection opportunities, part of the leadership entitlement package available to all heads".
See www.ncsl.org.ukresearchpublications and www.ncsl.org.ukresearchassociates for copies of the NCSL reports
What can heads do?
* Cherish your personal values, re-affirm why they are important to you.
* Develop an area of professional interest and take it beyond your own school.
* Seek professional time away from headship: on secondment, on detachment to another school or the authority.
* Make a link with another head, "a detached sounding board with similar experience".
* Be aware of the landmarks; at four or five years you move from "doing headship" to "being the head". At seven years you may be in danger of reaching a plateau.
What can councils do?
* Establish proper support networks - listeners, mentors - for heads.
* Train governing bodies to offer personal as well as professional "critical friend" support to heads.
* Ring-fence some professional development money for heads, who always put themselves at the end of the queue for funds.
* Offer alternatives to retirement - attachments to the authority for example - to heads on the "plateau" who may be thinking of leaving.