ST AIDAN's Academy, Darlington, is challenging the grades attained by 40 pupils in this summer's GCSE examinations in English. Although they were expected to achieve C grades or above, they were awarded Ds. As it stands, only 34 per cent of pupils will reach the crucial benchmark of 5 A*-C grades, including maths and English, compared with 44 per cent last year.

The C of E school serves the Eastbourne ward of Darlington, officially recognised as one of the most deprived in Europe. It has achieved a significant rise in standards since it opened six years ago.

After the GCSE results were announced last week, the principal, Alison Appleyard, said: "We are going to ask the examination board to review this as a matter of urgency." The assistant principal for standards, Stephanie Francom, said: "These results could limit the opportunities for our students in the future."

Hundreds of other schools, including other C of E secondaries, have been affected by the change in the English grade boundaries, which have reduced the proportion of pupils reaching the EBacc benchmark. In previous years, at least six or seven were included among the top 30 comprehensives. This year only two, The King's School, Peterborough, and Canon Slade, Bolton, made the list.

The guidelines required stricter attention to grammar, punctuation, and spelling, it is understood. Some schools are thought to have avoided the effects by entering students early.