Until May this year, King's Stanley primary school in Gloucestershire proudly displayed its Ofsted "outstanding" rating. It had come in 2009, one year after the school's founding, when inspectors raved about a school that was "truly a hub of the community", where pupils arrived each morning "with huge smiles on their faces" and parents left "with a smile too, rightly confident that their children will receive the best possible education". The headteacher, said Ofsted's report, was "truly inspiring", and when it came to her team of teachers, no stone was left unturned "in the quest for excellence in all that they do".

Four years on, the same head is still there. Classes are full, and the school is oversubscribed. Parents claim it may even have surpassed the standards it reached in the recent past, citing Sats results that improved 10% since last year and insisting that the staff do a "fantastic" job. But no matter: having issued a swingeing report that reads like an account of a completely different school, Ofsted has now deemed King's Stanley "inadequate" and placed it in special measures. That now means only one thing: separation from the local authority and conversion into an academy. The Department for Education has appointed one of its "brokers" to find the school a sponsor, and a local action group is fighting against a plan that scores of local people think is senseless.

As parents and teachers see it, what has happened has a simple plotline. To get a reasonable sense of the pros and cons of academy status, schools must register an interest in conversion. King's Stanley did that, and decided to not follow it up. Around three weeks after the matter was formally closed, the inspectors showed up – and before the Oftsed report was published, sparking 60 complaints and official appeals from both parents and the school itself, a letter from the DfE arrived serving notice that a broker was on her way. The whole process, says one campaigner, "seems to be engineered to force our school into becoming an academy". It certainly does.

Back when New Labour was in its pomp and pushing the first incarnation of the academies programme, there were rumours about inspections being cooked up for political purposes. I first heard them when I was covering an attempt to turn a secondary school near Doncaster into an academy, despite loud local opposition. In that case, the school was flipped from being "good and improving" and receiving a government special achievement award into special measures in just over two years, triggering a drive to hand it to the Emmanuel Schools Foundation, the charity created by Peter Vardy, a fundamentalist Christian car dealer from Durham. Thanks to local parents, the plan failed. In the decade that has since passed, similar suspicions have bubbled up from time to time: now, as evidenced by other stories from schools in places such as Cambridge, Croydon, Grimsby and Dollis Hill, London, concern is rising.

Inspections are contracted out to three private companies: Serco, the Tribal Group and CfBT, all firms with a vested interest in the onward march of private companies into state education. On occasion, more direct conflicts of interest have been uncovered: late last year, for example, the BBC found that at least four advisers working on the DfE's push for academies were also Ofsted inspectors. In general, though, the apparent harmony between government policy and Ofsted's work may be traceable to a much simpler matter of mindset: its head, Michael Wilshaw, is the former head of the Mossbourne academy in Hackney, and prone to sound as if he has imbibed a huge draught of whatever the education secretary, Michael Gove, is drinking. Small wonder that one teachers' union says its members now see Ofsted as "an arm of government".

There may be reasons why primary schools are now finding themselves downgraded and pushed into the clutches of outside sponsors: 49% of secondary schools are academies, but only 7% of primaries are. If the former are going to be viable, connecting them to primary schools is the obvious way to go, which explains some of the stories that have recently flared up. Critics of what the government is up to cite Roke primary in Croydon, repeatedly deemed "outstanding" but suddenly charged with being "inadequate" in 2012. It has since been given to the Harris Federation, founded by the carpet magnate Phil Harris, which is now in control of 27 primary and secondary schools. Among them is the former Downhills school in Tottenham, turned into an academy despite huge local opposition – some of which was focused on Ofsted inspections that saw the same inspector change her verdict of "improving" to "failing", thus sealing its fate.

Ofsted claims to be independent of any political agenda and tends to cite the tightening of its inspections framework, which has already led to 111 schools losing their "outstanding" status. But its detractors say that does not explain sudden crashes into special measures, and bemoan how little they can find out about how and why Ofsted's verdicts are reached.

When it comes to the observations and opinions that feed into finished reports, individual teachers can make freedom of information requests relating to their own work, and headteachers can do the same for a whole school – but what comes back is often heavily redacted. Outsiders have no such rights, so compiling sets of documents to compare and cross-reference is pretty much impossible. Ofsted and the DfE hold all the cards, and with the government having served notice that it wants to create 400 primary academies, it's pretty obvious why suddenly swingeing inspections have become such a big issue.

The apparent irony is glaring: under the auspices of a policy supposedly designed to free schools from the dead hand of government, the state's clunking fist seems to be falling all over the place with impunity, opening the way for a policy decided at the centre. The argument about academies and free schools is one thing, but this runs much deeper: even if they support what the government is doing to schools, people could be forgiven for expecting consistency, transparency and a model of government whereby ministers might understand that supposedly independent bodies have to be seen to be so, and that even the appearance of collusion can be toxic. Fat chance, it seems: the last lot thought they were above all that, and so do their successors.