Over recent months, a consistent theme of debate about education has been the need to break down the "Berlin Wall" between state and independent schools.
Repeated demands for independent schools to sponsor academies, and recent explicit calls from ministers for state schools to be more like private schools, have made the same assumptions. Firstly, that there is a need for a one-way flow of knowledge and skills from independent to state schools and, secondly, that the best way to achieve this is through state-led driving of publicly funded schools towards private-school leadership.
You might think that I would welcome such proposals, as United Learning, the chain of academies of which I am chief executive, is a unique collaboration between a group of independent schools and a group of academies. In fact, I think that these assumptions are fundamentally flawed and the success of our schools is based on explicit rejection of them.
The problem with the first assumption is best summed up by a comment made to me by a headteacher with a very strong track record of success and achievement in independent school leadership: "I take my hat off to these guys who run academies. I wouldn't last five minutes in that environment."
Or, to put it another way, context really matters in education. The great teacher in an academically selective school may not be a great teacher in an inner-city comprehensive school where pupils' attainment on entry is well below the national average. Equally, many of our excellent academy teachers would not be at their best in a private-school classroom.
United Learning is fortunate to have some fabulous head teachers – many of them as effective as any school leader you could find anywhere. But the truth is that not all that many of our independent school heads would be great heads of challenging academies. And vice versa.
The personal qualities required are not completely different. But once you've spent 20 or more years of your career successfully leading one type of school, you have acquired a set of behaviours for school leadership that are well embedded and thoroughly learned. Changing those behaviours and habits to suit another context is not easy.
The key to the success of what United Learning is doing is mutual respect. If everyone begins from the assumption that they may have something to learn, as well as something to give, collaboration is possible and can succeed.
If the sales pitch is that independent schools are morally obliged to rescue challenging urban schools, then everyone is left feeling patronised: the independent schools, who know what they do in educating children well is already inherently morally worthwhile; and the urban teachers and leaders, who have spent a career working flat out to offer opportunity to their students and know that someone who hasn't done it before won't be able to do it better.
That brings me to the second faulty assumption: that somehow a government-led drive to make state schools like independent schools is likely to succeed. In fact, the reason why independent schools are as they are is precisely because they are independent. And independent means, most of all, independent of government.
Now, I wouldn't have spent a large part of my working life in the Department for Education (where I was head of standards) if I didn't feel that government could make a big difference to educational standards. However, I don't think that it does so when it seeks to mandate or to enforce the adoption of particular practices.
I have seen governments (of all political persuasions) propose to require every school to have a school uniform, to play chess, to have before- and after-school care, to introduce a prescribed range of clubs, activities and societies – the list goes on. I never took a job in the department that was about making schools adopt a particular practice, because it didn't seem a good use of my time. I don't think it is how government has a useful impact. Indeed, none of the policies in my list above has worked.
No. The way to create useful, sustainable change is not to prescribe practice but to set schools free. Not to stifle teachers, but to allow teaching to grow as a profession. And the way to have more independent schools is to allow schools to be independent.
So, how do I think we breach this alleged Berlin Wall between the sectors?
First, we need an atmosphere of mutual respect, in which everyone is out to learn from everyone else. In my experience, great leaders are constantly looking for great new ideas and new methods to borrow. For example, within United Learning, if I go to the outstanding Paddington Academy, I will find ideas taken directly from independent school of the year Guildford High School, as well as other schools in the Group. And if I go to Guildford High School, I'll equally find ideas lifted from Paddington and other schools. Great leaders look to improve all the time. And when everyone is borrowing ideas freely, the barriers and the idea of a pecking order get broken down.
Second, a rigorous, evidence-based appreciation of excellence. We aim to identify excellence on the basis of evidence – qualitative and especially quantitative. Where analysis of data shows a real impact on how much children learn, the question of which sector it comes from is irrelevant. That is not to deny that there are areas of particular strength in one sector or the other. Our independent schools do have particularly strong extracurricular programmes, and they emphasise teachers' subject knowledge particularly strongly. Meanwhile, our academies tend to have very strong systems and emphasise teachers' pedagogical skill.
These contrasts are exceptionally valuable and provide a wonderful opportunity for colleagues to learn from one another. However, in being scrupulously evidence-based in our judgements, we avoid any risk of assuming that all the strength of a particular type always comes from the same sector.
Also key are the networks and relationships that allow people to learn from one another. For example, our subject networks bring together teachers from both sectors – sharing both subject knowledge and classroom practice. When you have real excellence in both within a network, the opportunities for learning are very great.
Finally, our approach is based on the joint development of practice between professionals. When we run excellence visits, allowing staff to examine excellent practice in one school, we don't expect that ideas from one place will be taken wholesale and then dropped somewhere else. Instead, leaders and teachers develop those ideas together and make them appropriate for a new context. So, ideas from Walthamstow Academy about improving attendance, Stockport Academy about student leadership and Surbiton High School about creative approaches are popping up across United Learning – but not in identikit format – subtly shaped to suit new contexts.
Does methods taken from tough schools really make a difference to high-achieving independent schools? David Levin, United Learning's new managing director of independent schools, has a unique perspective, having chaired a primary academy while running the excellent City of London School: "The approach to tracking pupils was so good, I applied it in my own sixth form and got the best A level results and Oxbridge entrance we'd ever had."
Jon Coles is chief executive of United Learning and a former director general for education standards at the Department of Education