The relative improvement has outstripped even that of nurses. Performance pay, introduced amid protests, turned out to be a way of giving the vast majority of teachers pay rises. Few of those who tried to cross the new “threshold” to the higher pay scale were turned down.

But times may be changing. As Tony Blair’s agenda of “education, education, education” slips away, the focus of both the main parties is switching to health. Education may get a smaller slice of the spending cake in the next five years. So it is vital that changes to the way teachers are rewarded are fair and transparent.

The Training and Development Agency is proposing that pupils’ exam results should be taken into account in determining pay, but there must be no return to the crude system of payment by results which was discredited more than a century ago. The agency suggests that the yardstick will be progress, not raw results, so that teachers in difficult schools will not be penalised.

This is tricky territory. Teachers in badly run schools have to work harder to make a difference than those with effective headteachers. That is just as true of pupils’ attendance and homework completion rates - also proposed as measures of progress - as it is of exam results.

Any system must acknowledge that you cannot measure teaching just by number-crunching. Department heads, who will conduct the new reviews, will have to take a wider view. What is a good teacher? Alan Bennett’s play The History Boys features two very different teachers, the focused and effective Irwin, who is prepared to abandon truth in the interests of exam success, and Hector, the charismatic and unconventional teacher who loves learning and hates tests. The boys passed their university entrance exams thanks to the knowledge and skills acquired from both.