Selective schools do best on progress as well as raw results

Data on schools' "value added" measures - released for the first time - also paint independent schools and special schools in a highly favourable light.

The statistics were published on Wednesday on the Department for Education and Skills website.

They are in revised 2004 exam results, which have now been checked by schools.

'All-through' score

Schools which select pupils by ability have always done well in the league tables of "raw" results.

But what has now been published for the first time is a "value added" score charting children's progress throughout their secondary years.

This assesses how much their attainment has risen from their final year in primary school in 1999 to when they took their GCSEs or other exams last year.

It is given as a score based around 1,000.

Ethos

According to the Department for Education and Skills, teenagers in comprehensive schools averaged a score of 984.

In grammar schools the figure was 1,021. In secondary moderns, 982.9 - just below the comprehensives' score.

Special schools - for children with learning difficulties - also do well on this measure. The average in community special schools was 1,013.2.

In independent schools - selective and non-selective - the average was 1,034.2.

Grammar schools say the figures prove that their ethos works, especially for children at the lower end of the ability range.

There has been criticism that the value added score is still far too crude, not taking account of such things as the social circumstances in which schools operate.

Education ministers have acknowledged that it needs refinement.

'Aim low'

The revised figures show that, overall, 53.7% of the nation's 15-year-olds obtained the equivalent of at least five good GCSEs in their exams last year - up from 52.9% in 2003.

The provisional figure, issued in October, had been 53.4% - a small increase is normal once the results have been checked.

This year's results took account of a far wider range of vocational qualifications, which official statisticians say inflated the total by 0.1 percentage point.

But the shadow education secretary, Tim Collins, said: "Giving vocational qualifications similar status to GCSEs in 'hard' subjects purely to satisfy Labour's ludicrous target culture does no-one any favours.

"It simply encourages an 'aim low' attitude to exams."

He said it undermined teachers' efforts to get less-academically gifted pupils to study valuable skills-orientated courses designed to improve their career opportunities later on.