GRAMMAR schools say they are perplexed by claims that a shake-up of how classroom standards are measured will expose how some selective schools "coast" on the back of having the brightest children.

Education Secretary Alan Johnson said in an interview that changes to the way children were tested were partly designed to show if the best-performing schools, such as selective grammars, did well because of good teaching or because they were able to cream off the more able children.

Kent has the largest number of grammar schools - 33 - in the country.

The Education Secretary said: "There could be, for instance, a grammar school that is thought of as being good but actually in terms of the quality of teaching and ability to lift kids beyond where they should be to meet their potential, it might not be as good as another school."

Government proposals will mean schools will in future be measured on the progress of each children, with pupils expected to move up to higher levels of attainment.

But Kent grammar schools insisted the current performance tables already showed they were better at "adding value" to pupils’ performance.

Lynda Wybar, the headteacher of Tunbridge Wells Girls Grammar School and chairman of the Kent and Medway grammar school association, said selective schools had nothing to fear from the changes.

She said: "It [the claim] is curious because the value-added measure in the tables already shows we do well between Key Stage Two and Key Stage Three. I think all schools will welcome the consultation on key stage testing at 11 and 14 because anything that will focus on learning rather than testing has to be welcomed.

The changes were welcomed by Labour’s spokesman on education at Kent County Council.

Cllr Roger Truelove said the changes were overdue. He added: "I don’t think there is any doubt that some grammar schools that select have a high percentage of GCSE passes but within those passes, a lot are at grade C when we should be expecting grades A and B.

"In parts of Kent, there has been coasting and I welcome the fact that the government is trying to be more flexible."