Education ministers must dread the publication of National Audit Office (NAO) reports. The latest retaining and developing the teaching workforce report follows a long NAO tradition of casting significant doubt on government policy and on the Department for Education’s (DfE) knowledge of what is happening in England’s education system.

Last year’s NAO report was on training new teachers. The NAO concluded that it could not state that the £700 million per year spent on teacher recruitment and training was money well spent. In this year’s report, the NAO says the government is also not doing enough to retain teachers in the classroom.

There can be no doubt that, as the bulge in pupil numbers moves from primary to secondary education, greater numbers of subject specialist teachers are needed. Secondary pupil-teacher ratios are rising, which means increasing class sizes or contact times for already over-worked and over-stressed teachers. Given that working conditions are going to deteriorate, and the fact that England has one of the worst teacher retention rates in the developed world (over half of England’s teachers last less than ten years in the profession), surely teacher retention should be a top government priority?

It appears not. The NAO notes - unbelievably - that “The Department has not set out in a coherent way and shared with schools and the teaching profession how they can work together to improve the teaching workforce.”

Teachers’ exodus

This NAO report arrives after the School Teachers’ Review Body (STRB) report, which did not mince its words when considering the vexed issue of teacher retention. In stark and forthright language, which I find unparalleled in any previous STRB report, the review body identifies three key reasons for the exodus of teachers from the classroom. These are the “pressures of high workload”, the “strict accountability system”, and the unattractive levels of teachers’ pay.

But the STRB goes further and issues a stark and unprecedented warning to the government: “Our analysis of the evidence for the current pay round shows that the trends in recruitment and retention evident last year have continued - teacher retention rates continued to fall, particularly for those in the early stages of their career, and targets for ITT recruitment continue to be missed. We are deeply concerned about the cumulative effect of these trends on teacher supply. We consider that this presents a substantial risk to the functioning of an effective education system...”

And there you have it.  Government ministers cannot, any longer, hide behind their wide-eyed “crisis, what crisis?” stance. There can be no doubt, now, that inadequate, and worsening, teacher supply is gravely threatening the effective functioning, and quality, of England’s education system.

Mary Bousted is joint general secretary of the National Education Union. She tweets as @MaryBoustedNEU

Want to keep up with the latest education news and opinion? Follow Tes on Twitter and like Tes on Facebook