Like many teachers, I’ve experienced intermittent bouts of disillusionment with an education system that can, at times, seem to embody an exam factory. Convinced that there was something better out there, a few years ago I trawled through job adverts in an attempt to find a school that approached education differently. I decided to look at new schools. That way, I figured, I’d be part of building something from the bottom up. So I took a teaching post at a free school that had been open for just under a year.

I wasn’t alone in my thinking. Several other teachers had also decided to embark on what they assumed would be an exciting challenge. We met and quickly realised that while our experience varied significantly – ranging from NQTs to experienced teachers – we all had one thing in common: optimism about the task ahead. We eagerly anticipated the start of term, but when September arrived it became clear that we’d misjudged the situation and made a terrible mistake.

It’s not clear how or why the Department for Education (DfE) makes its decisions on which free school applications to approve, and it has done little to clarify its methods when challenged. In this particular case, the group who had made the application appeared to be well intentioned, but once we were embedded in the school it became glaringly obvious that they were in over their heads.

Collectively, they lacked the sufficient managerial experience to run a school effectively and we were alarmed to discover that they had previously worked at a school with a poor Ofsted rating. In our eyes, this cast aspersions on the managers’ ability to create a good or an outstanding school. Unfortunately our doubts were soon vindicated.

Disruptive behaviour was endemic throughout the school, in and out of lessons. Everywhere you went there were children being yelled at – in the corridors, classrooms, and the canteen. “Inclusive teaching” meant dealing with whatever happened in your classroom, because the necessary structures and support were simply not in place. If you sent for a member of the school leadership team to remove a child from your lesson, they often didn’t come.

Some subjects didn’t have subject teachers, and unqualified teachers were employed in their place – something that happens at a higher rate in free schools than other schools. Usually these were graduate students who were keen to gain teaching experience before they took up places on teacher training courses.

Ill-equipped to cope with what confronted them in the classroom, the experience left many of them shattered. Predictably, there was a high turnover in classroom support staff, but it didn’t stop there. Having had our concerns downplayed or dismissed by our line managers and the school leadership team, a significant proportion of teachers left during the course of the academic year, wondering how things had gone so wrong.

Those of us still in post keenly awaited the imminent Ofsted inspection, but it didn’t happen. By the time Ofsted did arrive, I and many other teachers had already left. It raised serious areas of concern in its report and the school was graded poorly. There were no winners, only losers – namely the children who had been on the receiving end of an inadequate education; they deserved better.

I don’t pretend this is representative of what goes on in the majority of free schools, but 16 have already been closed down. And while the quality of free schools undoubtedly varies between regions, considering the area where my former school is located sets alarm bells ringing.

It is an area in which the majority of schools are rated as either good or outstanding. But other free schools here have been graded poorly by Ofsted. Clearly, the free schools in this area are not raising educational standards.

Would this situation have arisen if the local authority had retained overall responsibility for the creation of new school places in the area? It is unlikely.

Local headteachers have made their concerns regarding the establishment of free schools in the area known to the DfE. The local authority has also stated clearly that there is no need for additional school places locally. How then, is it possible that another application has been DfE-approved to open near to the existing free schools?

The economic argument against free schools is clear; the public accounts committee reported in April that the creation of new free school places costs significantly more than the creation of places by local authorities. And while free schools were introduced with the intention of driving up education standards by increasing innovation and diversity in our education system and encouraging competition between schools, a report published by the National Audit Office in February confirmed that the DfE has not been able to determine whether they are having the intended effect.

With no clear evidence that the programme is working, and serious concerns raised by teachers, local authorities and teaching unions, it is time for politicians to abandon their blind faith in free schools and listen to the experts. We need detailed local impact studies on the efficacy of free schools before any more children lose out.

Follow us on Twitter via @GuardianTeach, like us on Facebook, and join the Guardian Teacher Network for lesson resources and the latest articles direct to your inbox

Looking for a teaching job? Or perhaps you need to recruit school staff? Take a look at Guardian Jobs, the education specialist