Shortage of money is not by itself a satisfactory reason for not paying a fair rate for any job. But what is a fair rate for heads and deputies? As is so often the case when governors are required to act, both the guidelines and the data on which to base their decisions are inadequate to the task.
Governors may consider any factor that seems to them to be relevant. But they should be very wary indeed of claims based on comparisons with salaries paid in other schools. They do not know on what evidence other heads' increases elsewhere were based. Nor are they in a position to compare management responsibilities elsewhere.
The statutory requirement to consider the responsibilities of the post, difficulties in recruitment and the background of pupils are susceptible to reasoned analysis. But only if reliable indicators are available. In any case, they really only come into play when fixing initial salaries or where circumstances change.
The more performance-related criterion governors must consider, "sustained overall performance which appreciably exceeds that normally expected", begs questions about what is normally expected from heads and deputies. If the four-page description of heads' contractual duties in the statutory pay and condiditons document represents the norm, then appreciably exceeding this represents a very high hurdle indeed.
The independent teachers' pay review body suggests that before making such payments governors should set out the personal and school achievements that heads and deputies have to exceed to merit extra. That is something not many governors are likely to find very easy - or palatable.
It could, of course, spell out for senior managers the governors' high hopes in no uncertain terms. And that in turn could have a crucial impact on the level of expectations transmitted throughout the school - for good or ill, depending on whether the governors get it right.
But is it sensible to consider merit pay for senior staff apart and in a different way from that for all staff? A third of secondary heads seem to have received additional scale points for extra responsibilities and sustained performance in the past three years, whereas the numbers of responsibility allowances for teachers has remained broadly static. Only about one teacher in 100 has received additional salary points for "excellence", despite the growing numbers reaching the top of the pay scale.
Unless all staff can reasonably expect to be rewarded for sustained performance in excess of that normally required, teachers will reasonably conclude that, as with excessive payments made to directors of other recently privatised public utilities, there is one rule for the bosses and another for the bossed.
That is a particularly damaging thought to cultivate in schools which depend so heavily upon staff accepting mutual responsibility for ensuring that every pupil achieves his or her fullest potential.
An important signal of the reality of that collegiate partnership is the full inclusion of staff governors in drawing up and operating pay policies.
It is not a question of teacher governors drawing on their partial impressions of senior colleagues' performance to decide their pay; after all, other elected and appointed governors are in no position to make such judgments either.
What it must entail is fair-minded assessment of the evidence put before the governors' pay committee. And it sends out an important message about fairness being seen to be done if the elected staff governors are eligible to be involved in that process.