Hans van Broekman, principal of Liverpool College, writes:

We are told by the poet TS Eliot that the world will end with a whimper, not a bang.  A little reported speech of Michael Gove at the Brighton College last month contained the seed, which if watered and germinated by political will, will change independent education in England and Wales out of all recognition.

Mr Gove made no aggressive denunciation of inequality. No explosive legislative programme was mentioned. No class warfare was adduced. No attack on charitable status floated. No introduction of VAT on school fees suggested.

Instead, Mr Gove merely suggested that perhaps Ofsted should inspect all schools, rather than have the separate Independent Schools Inspectorate (ISI). With these simple words he placed a bomb under the operations, culture, attitude and privileges of every fee-paying school in the country and, I suspect, sent shudders down the spine of every headmaster in that sector.

We must hope that Mr Gove was not just ruminating, but intends to follow up on the idea. Inspection of all schools by Ofsted would finally allow for comparison between best practice in the fee-paying sector and state sector and effective sharing and communication of such best practice. In my experience, the comparison will, in many cases, dent the self-proclaimed superiority of fee-paying education whilst the communication of best practice will enrich the state sector.

Our school is experiencing the differences between ISI and Ofsted inspection regimes in a very real way. In 2012, we were inspected by ISI as an HMC fee-paying school and received a pleasing and affirming report from the inspectorate. Now, as a recently converted academy, we are preparing seriously for our first Ofsted inspection in the next academic year. Any governor, member of staff, or pupil in our school will tell you that one might AWAIT ISI, but you had better PREPARE for Ofsted.

ISI is a friendly peer-inspection regime. Of the nine people inspecting our school in 2012, seven worked in HMC schools themselves and one worked in a school we visit for sports fixtures annually. ISI does not give an overall grade to a school, preferring judgments in separate areas. This diffusion of judgment naturally has the effect of blunting the impact of any negative findings and making direct comparisons between schools impossible. No ISI inspected school may thus call itself excellent, or good, although many do, but neither can it be deemed inadequate or poor overall.

ISI inspection reports are longer, more narrative in style, and usually better written than Ofsted reports. But it is impossible for anyone reading the report to know how the school compares overall to others and even compared to the criteria of the inspection framework. There is no such thing as a fee-paying ISI-inspected school in special measures although ISI does follow up in schools where compliance with regulatory requirements is found wanting, something that happens with some regularity in some cases.

These arrangements suit independent schools.

So what is the difference now we face Ofsted? We have found the biggest difference between the regimes is the emphasis on teaching. The quality of teaching is a brutally clear judgment that jumps off of the page in an Ofsted report.

In our 2012 ISI report, it was encapsulated in judgment 3(c) “the contribution of teaching” and as such is a subsection of the section Academic and Other Achievements. Good results can therefore mask or make up for poor teaching. In our ISI report, teaching was one of nine judgments, not one of four as it will be in Ofsted’s report.

In an Ofsted report, it is difficult to be outstanding without outstanding teaching. Our 2012 ISI report proved that you can be judged excellent in many areas of an ISI report without a focus on teaching. In an Ofsted inspection, teaching will only be deemed outstanding if the leadership and staff are totally dedicated to and effective in sharing and implementing best practice, promoting professional development, action research, curricular coordination, collaboration and innovation in teaching, appraisal and evaluation and what can best be called a “buzz” for learning, palpable and visible in the school. In our experience, this requires making teaching a much higher leadership priority than it is in most fee-paying schools.

Since becoming an Ofsted-inspected academy, we have found that leadership’s focus on improving teaching has overtaken our previous focus on marketing, fundraising, financial matters, facility development, sports fixtures, and even pastoral arrangements. It has taken some getting used to, but it has certainly meant better teaching and less complacency about the quality of teaching. We feel strongly that this is in the interest of our pupils. Indeed, it may be the best thing about becoming a state school.

There is no better evidence for this comparative emphasis on teaching than the way independent schools organise their leadership. You will have to look long and hard to find a senior leader in an established fee-paying school whose title resembles “head of teaching and learning”. Where the position does exist, it sometimes has no salary or stipend attached to it and its holder is not on the management team. Appraisal and observation regimes, learning walks and peer observations in independent schools are, in our experience, less developed than in Ofsted-inspected schools. ISI does not scrutinize such regimes to the extent Ofsted does.

The very title of “director of studies”, so commonly used for the person who is de facto in charge of the quality of teaching in a fee-paying school, implies a very different approach to the improvement of teaching than the one’s recommended by Ofsted. The title suggests quiet confidence that all teachers are self-directed, naturally-ideating professionals whose teaching is of Olympian excellence and who merely need to be co-ordinated into a timetable and curriculum plan.

My experience is that pupils in these schools do comment on the mixed quality of teaching and how poor teaching is sometimes tolerated by the leadership of the school. In most Ofsted-inspected state schools, appraisal, improving practice and capability procedures are constantly identifying poor teaching and addressing it in anticipation of an Ofsted verdict on teaching.

I asked a famous HMC headmaster once how he refreshed his staff. He answered that he paid off unmotivated staff members. This option is not available to every state or fee-paying school, but it hardly attests to a culture of continuously improving teaching.

My erstwhile headmaster colleagues in HMC always believed that the market was their true inspector. In some sense of course this is correct. An independent school is accountable to fee-paying parents.

However, parents are impressed with many things not related to the quality of teaching. Ofsted inspection of fee-paying schools would shine a proper independent and comparative light on teaching those schools. It would also reveal some of the “secrets” of fee-paying education to the country. I suspect it would, as it has done in our school, substantially raise the quality of teaching for all pupils in the country.