No one doubts that the existing specialist schools produce better raw exam results. The question made more pointed by the Government's enthusiasm for encouraging all schools to specialise is why? Has it anything at all to do with specialisation? Or is it more to do with intakes, better leadership, more money and the staff they are able to attract?
At the specialist schools movement's annual meeting this week - now probably the most prestigious event in the education calendar and able to command Ted Wragg, schools minister David Miliband and the Prime Minister as speakers - much was made of their estimated eight-point lead in the percentage of top grade GCSEs.
Ofsted and others question whether it is specialisation as such that produces this (page 6). A National Foundation for Educational Research study, meanwhile, has looked at what it is that makes these schools successful. It lists nine separate characteristics such as outstanding leadership, high expectations, effective use of ICT and support staff and extensive monitoring of pupil progress.
In other words they are good, well-managed and successful schools, which is hardly surprising. Any school that is not finds it impossible to jump the necessary hoops to qualify. Specialist schools may not be selective. But they are selected.
Specialisation is not one of the success factors identified by the NFER. Nor is it discussed much at their annual meeting. It seems largely irrelevant to this convivial club of like-minded, can-do, entrepreneurial schools. Much more important is that they are prepared to accept that they are accountable for ensuring that the potential of every pupil is realised.
With 1,007 full members and a further 800 affiliated schools, it is no longer even a particularly select club, though their enhanced ability to attract and keep scarce staff may make it progressively more difficult for others to join.
But what these reform-minded schools have achieved is to convince Tony Blair that he cannot impose real school improvement from the centre and that he has to unleash their creative and innovative professionalism if he is to achieve his aim of giving every child a chance to succeed.