exam performance in a way that does not produce league tables of raw results, powerful support has come from south of the border.

The National Audit Office, in a report on the exam performance of a million children in England, calls for an overhaul of league tables and says the use of raw scores in traditional tables is of “limited value” in judging schools.

The NAO has produced its own measure for key stage 3 (14 year-olds) and GCSE performance. This takes account of pupil backgrounds in 3,100 English secondaries. One in 10 of the bottom 20 per cent in 2002 should have been rated among the top 20 per cent, it calculates.

The report warns that the Office for Standards in Education pays too much attention to raw scores and not enough to pupils’ background. “Decisions to place a school in special measures might also be influenced more by the unadjusted academic achievements of pupils,” it says.

Of the 72 schools in special measures during 20012, 78 per cent were ranked higher by the NAO at KS3 and 65 per cent at GCSE.

Seven years ago, Chris Woodhead, the then chief inspector, stopped inspectors taking more account of pupils’ social background.

The auditor’s report raises serious questions about the Government’s use of exam results as an indicator of school performance.

Of the 624 schools ranked in the bottom 20 per cent of performers in KS3 tests, just 196 remained there when scores were adjusted for external factors and 87 moved into the top 20 per cent. This also calls into question whether setting the same minimum targets for schools and councils, regardless of external factors, is sensible.

When external factors such as pupils’ previous attainment, social deprivation, ethnicity and gender are taken into account, schools which appear at the bottom of league tables are among the country’s best, it found.

Five London authorities normally judged as among the worst in the country all perform better than the national average at KS3.

David Bell, chief inspector of schools, and David Normington, permanent secretary at the Department for Education and Skills, will be expected to justify their approach to MPs on the public accounts committee next month.

The NAO called for the Government to make adjusted results the key measure of school performance. The Department for Education and Skills said the Government already publishes more sophisticated information alongside raw test scores. For the first time this year value-added measures will be included in all three tables - primary, key stage 3 and GCSEpost 16.

The Scottish Executive has dropped the national publication of school-level exam tables for the first time this year, issuing only national and education authority average figures.

It is expected to unveil a website in a couple of weeks’ time which will guide parents to exam results for their own and other schools in which they may be interested. But this will be in conjunction with other performance outcomes which will eventually be linked to the five national priorities for education, of which attainment is just one.