Education is in many ways treated like a market, like a commodity sold to the schools by the government and then to the students by the schools. Examination entries are literally sold to schools; doesn't that seem strange? Why do we put a critical component of the education system in the hands of non-governmental bodies whose primary motivation is to stay in business?
Not only does this present schools with unnecessary choices, it puts unwholesome pressure on the exam boards themselves. When exam boards depend on uptake to pay their bills, they must compete with each other for the attention of the school officials. When grades are standardised on material covered and schools are under pressure to produce high grades, they put exam boards under pressure to cover that material in increasingly straightforward ways. People complain about declining standards, but don't recognise that all the bodies involved are under constant pressure from our policies to push that standard down.
The competition between exam boards and schools isn't the only place where misapplication of market principles results in skewed motivations. The schools put pressure on the exam boards to make things simpler for them because they are themselves under pressure to produce results. In principle this might seem like a sensible idea, ensuring that schools are held to account for their successes or failures, but there are several unwanted and unnecessary side effects. Since high position in the league tables is associated with prestige and desirability, such tables have the dual effect of simultaneously making students compete for school places and schools compete for students. Exam performance of a school measures good education at best only indirectly, rating a school that takes in gold and produces gold above those that take in ore and refine it into steel. Mineral analogies aside, the best schools select the best students, who go on to produce the best results: we set up a system whereby those schools that demonstrate most clearly their ability to do their job are given the easiest job to do. Meanwhile, on the other end of the spectrum, the failing school is viewed with a mixture of pity and scorn, and everyone seems to try their best to pretend they don't exist. This is the complete opposite of what we need to do to preserve nationwide equality in educational opportunity.
In conclusion, we need urgently to stop treating education like a free market: nationalise the exam boards, unify them, make them accountable to the people who genuinely need their results to remain high quality: the universities and employers who use them. Stop pretending that schools have the right to choose children or children to choose schools: if there are schools worth choosing then the only way to ensure consistent quality is to invest in those not doing so well until parity is restored. Parent choice is an appealing buzzword, but it's impossible: until all schools are up to standard, there will always be children left behind.