Dickon Snell, deputy head of Maiden Erlegh school in Reading, has already dashed off his protest letter to David Blunkett. This summer, the school had 65 per cent of pupils achieving five passes at grades A* to C but has been given a lowly “D” rating for progress.

Mr Snell believes the school is being penalised for having good key stage 3 results, and is being compared to grammar schools where pupils enter for 10 or 11 GCSEs (Maiden Erlegh pupils usually enter for nine). “We see the hours and energy spent, and the bitterness and resentment that’s caused by these things. They will have egg on their faces if they publish this because it’s so crazy,” he said.

Susan Court, head of selective all-girls Gravesend grammar, has similar concerns. Her pupils also usually take nine GCSE exams. “The school has had its best-ever GCSE results in terms of the percentage of A* grades, and 100 per cent of our pupils got five A* to C grades. Then suddenly we are a “D” band school doing less well than others,” she said.

But David Abbott, head of Pittville GM school in Cheltenham, is “over the moon” about his school’s “A” grade. The pass rate for five good GCSEs has risen from 17 per cent to 47 per cent in five years. “I’m in quite a competitive area, with grammar schools. We come fairly low down in the pecking order. This gives me a counter-balance to the other side of the tables, that always seem to promote the schools with the best intake,” he said.

“If you are doing the job right, whatever quality year group you have got, you should be adding value, and if you can always remain in the A to C band you are doing well.”

Karen Thornton