Headteachers are phenomenally important. We know that a good head can turn a school round and transform the life chances of the children who attend it. But even good heads need to be held to account - and heads who are not up to scratch need someone to boot them out.
In the commercial world, it is customers who keep managers on their toes. If one branch of Tesco is badly run, customers will start to shop elsewhere and takings will fall. Tesco headquarters in Cheshunt will notice within days that something is wrong and will ask why. Sometimes there is a good reason - roadworks in the area mean customers cannot get to the store, for example. But sometimes there are no good reasons and managers higher up will intervene.
There is no such early warning light to tell us when schools are underperforming. Parents can take their children away from a school and into another, but it is a nuclear option that few exercise. Parents applying know relatively little about a school when they are choosing a school. So we need other forms of accountability.
Commercial chief executives are accountable to a board of directors and to shareholders, via an annual general meeting and an annual report. School heads are responsible to their governors, but the overwhelming sense is that governors are a body of people who receive information, rather than people who are there to run things. Only on really big issues - should a school expand, who should be the next head - do governors feel that they are making the decision in consultation with the head.
That needs to change. Successful systems of governance in both the private and public sectors are characterised by a system of checks, in which everyone is accountable. Governors need to be part of that.
In an ideal world, every school would have an effective board of governors, each with plenty of time and with high levels of expertise and experience. Realistically, life is never going to be like that, so we need to do things that will help governors to hold heads to account.
First, schools have to give governors real information, quantitative and qualitative, in a timely manner. This has to relate to the school as a whole, but also to individual teachers within the school. We all know - from our own school days, if nothing else - that there are effective teachers and ineffective teachers. Heads know this better than anyone and need to be honest with their governors about how individual staff are doing so that the governors can hold heads to account and find out what they are doing about the problems.
Do staff need coaching? Assisting? Booting out? Any head who does not make this sort of information available is failing the children in their school (and the Government is failing all of our children by making it so hard to get rid of underperforming teachers).
Governors also need to hold heads to account on how schools spend their money. There is good evidence that teaching assistants do not work, in so far as classrooms with teaching assistants do not have better results than those without them. There is also precious little evidence that cutting class sizes slightly is effective. On the contrary, there is evidence that reading recovery is hugely effective and that synthetic phonics works. Heads need to explain to governors what the options are, and why they have made the decisions they have. And governors need to be challenging them on those decisions.
To help governors in that role, the Government needs to be briefing them. Ministers are famous for liking their briefings in 16-point type and no longer than a page. Such a briefing contains about 300 words, a third of the length of this article. Civil servants who have written these can tell you that it requires effort to write that concisely, but that it is a very effective form of communication. This would be a good model for the sorts of briefings that the Government should prepare for school governors. It is perfectly possible to set out the evidence that teaching assistants are not good value for money in 300 words. Such a briefing would include the intuition and the evidence, as well as references.
Finally, governors need sanctions. The ultimate sanction is to remove the head. A good head is so critical to our children's education that we need to be able to get rid of those who are simply not up to it. Heads should not be on permanent contracts that make them very hard to remove. It is hard to change existing contracts, but new heads should be appointed on 12-month rolling contracts, which governors can extend - or not - each year.
Making the role of governors into a proper one will make the job more attractive. In turn, that will help to attract good people to become governors. Heads should be expected to be a governor of another local school, just as people in business often have non-exec roles outside their own business. There is no conflict of interest if a primary head is a secondary governor, for example.
We should also look to retired teachers and heads to be involved. There is a wealth of experience here to be tapped. Those with non-executive experience should also be sought. But at the heart, we need parents who are prepared to demand high standards, who are willing to look their child's head in the eye and say, "You have a responsibility for my child's education and I am going to hold you to account for what you do." Then we will get the schools that our children deserve and our country needs.
Tim Leunig is chief economist at liberal think-tank Centre Forum and reader in economic history at the London School of Economics.