A report by the Hay Group, based on UK-wide evidence, suggests that to fill a predicted minimum of 2,500 headteacher posts in Scotland over the next few years, as many as 25,000 future leaders need to be developed in middle and senior management posts.
But Neil Paterson, director of the Hay Group in Scotland, believes not enough is being done to groom those in the middle ranks to take over the top jobs. "Any successful organisation needs to take action to make sure it has the right people in the right places at the right time to do the right things," Mr Paterson said.
"This simply isn't being given enough priority within education at the moment."
Mr Paterson called for "specific and systematic action to create a leadership pipeline" so that a bigger pool of high-calibre candidates is available, going beyond those needed purely for headships. "The traditional model of the single powerful person at the helm is outdated," he said.
If the situation continues to be left to chance, Mr Paterson said, "headteacher posts will be filled with reluctant leaders who are destined to fail themselves, the school and the thousands of pupils who pass through a school during that person's time in charge".
The Hay Group's report says the failure to act will be reinforced by a "demographic time bomb" which will see more than half of the teaching profession reach 50 by 2006.
The Scottish Executive believes the position will improve with standards for initial registration, chartered teacher status and the qualification for headship, which is aimed at aspiring headteachers and will become a mandatory requirement for heads by next year.
Anne Pearson, who is in charge of continuous professional development in Clackmannanshire's education department, acknowledged that, while those being identified as potential leaders are already deputes, teachers need to be targeted much earlier in their careers," she said.
"It amazes me that people with leadership potential are not identified early, or encouraged by being told that they have the potential to be a future leader.
"Class teachers need strong leadership qualities to be able to motivate a class of pupils. These skills can be developed, but it seldom happens just by chance. Local authorities and schools cannot afford to treat leadership as an extra-curricular activity."
The Hay Group predicts that the problem of finding good leadership material could be most acute in rural areas, which already have problems in recruiting staff.
Growing Tomorrow's School Leaders: The Challenge, by Frank Hartle and Katherine Thomas, is available on www.ncsl.org.uk researchpublications.
Six of the best
Hay's "talent-spotting" approach has six ingredients:
* create a culture for growth
* benchmark current practice against approaches elsewhere
* define what leadership qualities are needed
* identify the leadership talent pool
* assess individual talent
* grow leadership talent