Walk into a school and some things will strike you right away. Is the atmosphere respectful and warm? How do children interact with their teachers? What sort of project work takes pride of place on the corridor walls?

One thing that you can’t immediately tell from wandering from classroom to classroom is whether the school is an academy, run by a not-for-profit organisation independent of the local council, or a “maintained” school under local council oversight. When things are going well, parents may barely notice the difference. But when things are going badly, it matters and that’s why the extraordinary growth of academy schools has become one of the most hotly contested developments in education policy.

Last week marked an important milestone in the English school system: more than half of pupils are being educated in academies. It has been an astonishingly rapid transformation: the Labour government left around 200 academy schools in 2010; today, there are more than 8,000.

The debate can often feel polarised between those who think this a tremendous development and those who argue that we need to turn the clock back. Seven years in the hardest job I’ve ever done tells me the truth lies somewhere in between.

When I bowled up at the gates of a local primary school almost a decade ago, I thought that having written a couple of thinktank reports on education policy would make me well equipped to be a school governor. Boy, was I wrong. If you’ve never stood at the front of a classroom, there’s a dauntingly steep learning curve to effectively undertaking the “support and challenge” role of a school governor. In seven years, I never felt like I mastered it.

During my tenure, our school converted into an academy, which gave me a flavour of the pros and cons of both arrangements. As a maintained school, the support we got from the council was sometimes brilliant, sometimes poor; in some areas of the country, it’s consistently great or terrible.

When I joined, the school was struggling; we eventually managed to recruit an amazing head who produced an outstanding Ofsted judgment in just five terms. It always struck me as a waste that such an exceptional leader was in charge of the education of 300 kids rather than 3,000. Meanwhile, the then Tory education secretary, Michael Gove, was putting rocket boosters under Labour’s academy programme and brought in business and philanthropic leaders to transform a small number of struggling schools, with mixed results. Despite that, Gove wanted to turn far more schools into academies – his vision was for a market-based approach to school improvement. Competing organisations would run chains of schools outside local government control, while failing schools would be taken over by high-performing chains.

Facebook Twitter Pinterest Then education secretary Michael Gove with pupils of Durand Academy primary school in Stockwell, south London, in 2010. Photograph: Stefan Rousseau/PA Archive/Press Association Ima

There was a massive inbuilt flaw to this idea: once an academy trust takes over a school, it ceases to exist as a legal and financial entity – it is wholly absorbed. The only way out is if a trust is doing so catastrophically that the government forces it to give up its schools.

There are some brilliant academy chains – and some that are desperately failing. But the government now forces all struggling schools to join a chain and there aren’t enough good ones, so many end up joining, at best, the average performers. Too often, the chains they join can’t cope, which means that the situation in a school becomes worse, not better.

A damning public accounts committee report last week highlighted how it can become all but impossible for parents to get answers when this happens and it can take years for schools to get “rebrokered” from a failing trust to a better one.

I know from experience. We converted to an academy while our head was in place, in the hope of building a small group of schools to provide a good education to children in less affluent communities like ours. A year later, she had to move for family reasons and everything started to fall apart. We advertised twice for a replacement; no one good enough applied and in the months that followed much of the rest of the leadership team, and then the staff, moved on. We knew that without a good head there was no way the tiny trust we’d created could turn things around again and that we had to find another chain to join. It took more than two years to make that happen – navigating all the government bureaucracy and finding a trust that was a good fit and was willing to take us on. Many struggling schools have financial problems and it can be virtually impossible to find a trust willing to take on their deficits and crumbling buildings.

Financial accountability has been another disaster zone. The government naively trusted that setting up academy chains as charities would be enough of a safeguard and blithely signed away vast school assets – buildings and land – in the hope that they would be looked after. There was a lack of checks and balances and there have been several high-profile cases where heads and directors channelled funds into family companies under dubious arrangements, while buildings have been left to deteriorate.

Turning back the clock altogether would mean ditching the kernel of a good idea buried in the Goveian reforms: that great school leaders should be in charge of several schools. But the system urgently needs a fix.

One way would be to make academy chains accountable to local government, not the Department for Education’s opaque network of regional schools commissioners. Schools must remain individual financial entities so councillors and parents can get them moved out of failing chains. And politicians need to ditch their obsession with school structures and focus more on what is by far the most important question in education policy: how do you foster brilliant teaching and leadership in areas of the country where there simply aren’t enough good state schools?

• Sonia Sodha is an Observer columnist