Specialist schools first appeared in 1993 as technology colleges, when the Conservatives' more ambitious city technology college programme stalled through lack of money and local hostility.
Labour embraced specialist schools enthusiastically after 1997, by which time arts, sport and languages had been added to the range of specialisms. While there were just 222 specialist schools in May 1997, there will be 1,448 this September - 46% of secondary schools in England. The government has removed many of the barriers preventing schools from acquiring specialist status but the programme remains controversial.
Critics say specialist schools, where 54% of pupils gain five good GCSEs compared with 47% in other state secondary schools, do better because they can select up to 10% of pupils according to their aptitude in the school's specialism.
Others say specialist schools succeed because they get more money.
Specialists receive an initial £100,000 capital boost, provided they raise £50,000 from business. They also get a £126 per pupil premium for up to 1,000 pupils.
However, while some schools apply for specialist status to receive the extra money, far greater funding differences exist between similar schools in neighbouring councils, with no effect on results. When specialism is open to all, the money no longer becomes an issue.
But there are more serious challenges ahead. With 10 specialisms now available - including engineering and humanities - parents in urban areas could have a much better choice with a range of specialist colleges in their city or town. Indeed, if s tandards are seen simultaneously to improve - and the government is pledging to allow popular schools to expand - the elusive promise of real parental choice could become a reality.
Moreover, Labour insists that specialist schools have to use a third of their extra funding to work with other schools, so imaginative partnerships could develop which offer students a real choice of well-funded facilities and teaching, regardless of where they enrol.
But some schools may decide not to embrace specialist status. Rural schools may feel that embracing a single specialism undermines their breadth, despite the fact that most specialist schools do better generally, not just in their chosen subject. Specialist schools must teach the full national curriculum.
Unless the programme is to be fatally undermined, schools applying must continue to be able to show that they can improve with specialist status. That means there may always be some failing schools which are excluded from the programme until they do better. And schools missing their targets must still be able to have their specialist status and funding withdrawn, otherwise there is little incentive to improve.
The real reason why successful specialist schools have thrived has been because they combine strong leadership and ethos with a clear vision and challenging targets. And these secrets of specialist school success must not be dissipated in the rush to provide specialism for all. Otherwise, government reformers would have to return to the drawing board.