Schools with just a handful of pupils passing GCSEs in English, maths or science are scoring outstandingly well in a new rating system that is now central to all inspection judgements, The TES can reveal.

Some secondaries with fewer than a quarter of teenagers gaining a good pass in these subjects are among the top-performers in England under the new measure.

The new Contextual Value Added (CVA) rating system, now seen as the key to success in inspections, puts these well ahead of several schools where every pupil achieved five Cs or better at GCSE last year.

Among those left trailing under CVA are some grammar schools and the London Oratory, the former grant-maintained secondary in Hammersmith, west London, which Tony Blair chose for two of his sons.

The findings of a TES analysis will be seen by some schools as welcome acknowledgement of the quality of inner-city secondaries. But others believe that it undermines the new rating system.

CVA ratings appear to be heavily influenced by General National Vocational Qualifications, which controversially count as worth four GCSEs.

It is designed to assess the progress pupils make, taking account of how well they did in tests earlier in their schooling and other factors, including social background and gender.

Earlier this year, 370 schools agreed to have their key stage 4 CVA results for 2005 published. The TES compared these scores with some of the schools’

detailed GCSE results, obtained under the Freedom of Information Act.

The fourth-highest rated school under CVA was Parkside community technology college, Plymouth, with a score of 1051. The national average is 1000.

Heads have been told that schools scoring above 1024 are likely to get outstanding verdicts in the results section of their inspections.

Yet only six of Parkside’s 52 Year 11 pupils last year (12 per cent) achieved an A*-C in English. Seven (13 per cent) did so in maths. Three (6 per cent) achieved a good grade in double science and none did so in a language, or history. All 31 Parkside pupils who entered a GNVQ in information technology passed it.

Walker technology college, Newcastle-upon-Tyne, achieved a CVA of 1033, also comfortably “outstanding”. But only 21 per cent of pupils achieved A*-C in maths. None of the 83 entrants for GCSE science achieved a C or better, while just 6 per cent of entrants did in a language.

Of the top 20 schools in the CVA ratings, 11 had less than a third of pupils achieving five Cs or better including English and maths.

The London Oratory, where 92 per cent achieved five Cs or better, was 75th on the CVA list, with a more modest score of 1019. Five girls’ grammars where all pupils got five good GCSE passes received below-average ratings.

Valena Jones, Parkside’s head, said its high CVA score reflected the low starting points of its pupils: 40 per cent had achieved the expected level in English at key stage 2, and only 39 per cent in maths.

Steve Gater, Walker’s head, said: “The system will judge the value added of schools in different ways. We are rightly proud of the fact that our students are achieving highly within this system.”

* warwick.mansell@tes.co.uk