Today is the final day of one of Europe’s biggest annual gatherings in education. The Specialist Schools and Academies Trust (SSAT) conference has drawn more than 2,000 school leaders to Birmingham.

We have come together at a period when schools face tougher financial times, with the Government no longer funding specialist work separately from the general schools budget. Our critics say this means specialism has been sidelined. However, the delegates here can testify not only to what specialism has already delivered but how much more it can deliver in the future. And it would be wrong to imagine that cuts in direct funding spell the end of specialist schools or of an approach that has greatly improved English secondary education.

Our 5,000 schools in England and overseas believe that schools are best placed to lead change and reform. Our organisation is led by its members, particularly school leaders who have an appetite for improvement firmly grounded in excellent practice developed in the classroom.

I won’t pretend that we are happy that the Government has decided to end discrete funding for specialism. Since my fellow heads and I lobbied hard for its retention in our regular meetings with education secretary Michael Gove, we were very disappointed by his decision. But given that other grants paid directly to schools were also removed to pay for the pupil premium, we also recognise that the Government was unlikely to retain our specific grant.

But specialism is about more than extra money. Most schools went specialist because they believed it would be good for students. And Ofsted says they were right: over the past 15 years, the specialist programme has transformed half of specialist schools and had a positive impact in 95 per cent.

That is because specialism has fostered a new, more distinct character and ethos in schools. There has been a strengthening of school leadership as a result, backed by a more effective use of data to identify where interventions and improvements are best focused. Specialist schools have pioneered the effective use of information and communications technology and provided unparalleled subject networks that are engines of expertise.

So it is vital that the expertise that we have developed through specialist schools is not only retained, but is built upon. And it is crucial that we seize the opportunities offered both by the greater independence promoted by the Government and the pupil premium to demonstrate our ingenuity and innovation as never before.

I believe there are several ways that this can happen. The first lies in the development of subject expertise. With more than 90 per cent of secondary schools and academies having at least one specialism in subjects such as science, technology, languages, sport or arts, a huge well of expertise has developed that can play a big part in the transformation of schools in the years ahead.

At language colleges, 88 per cent of students take GCSE languages compared with 40 per cent in other schools. They will be critical to any revival of modern languages in secondary schools and to the development of primary school languages teaching. They are pioneering teaching in economically important languages such as Mandarin and Arabic. Science colleges have been at the forefront of the revival of physics and chemistry, with a big improvement in the take-up of triple science at GCSE, after years of decline.

These subject networks are well placed to test the impact of innovations such as the proposed five-subject English Bac but also to spread expertise in these subjects rapidly.

The second major opportunity is in closing the gap between pupils of different backgrounds and building a school system that is not just continuously improving but also competes with the world’s most successful education systems. The pupil premium can help provide the resources, but the networks developed by specialist schools will be vital in providing practical ways to enable those resources to make a difference to the lives of the poorest students.

With more schools hoping to adopt academy status or start as free schools, our practical help can ease the process, and will be particularly important supporting primary schools that may otherwise feel isolated when they decide to change status.

At the same time, our unique international network, with schools from Australia to Abu Dhabi and Chile to China, gives us a unique insight into what world-class education really means - and the challenges facing our young people in the global economy.

John Townsley is head of Morley High School, Leeds, and chairman of the SSAT headteachers’ steering group.