These schools add substantially more value over the full period of secondary education than do other schools

Professor David Jesson

At A-level, pupils in specialist schools scored an average point count of 16.45 in 2000, compared with 15.52 for other non-selective schools.

The research also found that, in areas of high social deprivation, specialist schools did especially well.

The results were good news for the government, which wants nearly half of all comprehensives in England to become specialist schools.

Controversial scheme

Specialist schools have been controversial, because they get extra funding from the government to become centres of excellence in a subject area, such as technology, the arts or modern languages.

Critics of the system have accused the government of creating a two-tier system where most state schools lose out.

The outstanding results of specialist schools in 2000 at GCSE and A-level give strong support to the government's proposal to expand the number of specialist schools

Sir Cyril Taylor

But Professor Jesson said: "The value added performance of specialist schools is remarkable - 43% of them appear in the 'top quartile' of value added performance, compared to only 22% for other comprehensive schools."

"This indicates that these schools add substantially more value over the full period of secondary education than do other schools.

"This advantage is also apparent at the other end of the scale where less than one in ten specialist schools have very low levels of value added - this compares to 27% for other schools," Professor Jesson said.

'Outstanding results'

The results of the survey were welcomed by the chairman of the Technology Colleges Trust, Sir Cyril Taylor, who advises the Education Secretary, David Blunkett, on specialist schools.

"The outstanding results of specialist schools in 2000 at GCSE and A-level give strong support to the government's proposal to expand the number of specialist schools to 1,500 by the year 2006," Sir Cyril said.

But campaigners for comprehensive education said the research showed the government was wrong to limit the number of schools permitted to become specialist.

"If it is of benefit, why are we deliberately denying that benefit to half of all secondary school children?" asked Margaret Tulloch of the Campaign for Real Education.

"We still don't really know why specialist schools are more successful and until we do it is reasonable to say it is the extra money that must have an effect," she said.