Thousands of teenagers across the Midlands celebrated A-level success yesterday as a leading head teacher warned that "grade inflation" was fuelling record results.

John Claughton, headmaster of Birmingham's top private school, King Edward's, dismissed as "nonsense" claims that brighter students and better teaching were responsible for nearly one-in-four exam entries resulting in grade As.

He said a dramatic surge at his school, which has had a stable group of academically gifted pupils for decades, clearly showed it was now easier to achieve top grades.

Mr Claughton spoke out as Ministers defended the 24th successive increase in the A-level pass rate to 96.6 per cent. The number of entries awarded an A-grade rose from 22.8 per cent last year to 24.1 per cent.

The Department for Education and Skills claimed the results were the sign of a successful education system in which growing numbers are staying on and achieving.

But Mr Claughton said: "On results morning, politicians will say they want to congratulate teachers and pupils. To some degree, teaching is more professional and pupils are working harder.

"But in all honesty it would be hard to equate the extraordinary growth in these rates at A level as all generated by the fact that kids are brighter and teachers are working harder.

"We are a valuable benchmark because the quality of our students and staff has remained stable.

"The grade inflation since 1976 is absolutely massive. Thirty years ago out of hundred boys in the school maybe ten or 15 would have got straight A grades.

"Now I would expect the figure to be close to 50 per cent.

"Anyone who tells you that this is because standards have increased, is talking a load of nonsense."

Nationally, there were five schools with 90 per cent or more of grades awarded at A and B grades in 2000. Last year there were 32.

At King Edward's, a fee-paying boys' school based in Edgbaston, 56 out of 115 pupils achieved three or more A grades. The proportion gaining A or B grades was 89 per cent.

"Such numbers would have placed us 6th in 2000, and will probably place us 30 or 40 places lower in 2006," said Mr Claughton.

"To come 100th in these tables in 2000, you needed to score 67.1 per cent. To come 100th in 2005 you needed to score 80 per cent. That is grade inflation, I'd say."

Schools Standards Minister Jim Knight, however, said claims about lower standards were "the same old tired assertions" and a false argument.

The Association of Teachers and Lecturers also condemned the annual debate over whether A levels have been dumbed down as "futile, irrelevant and boring" but the National Union of Students called for "an open debate" on changes to the qualifications system.

* An A-level student was killed yesterday as she drove to get her exam results.

Kelly Rice, aged 18, of Ryall, Worcestershire, was driving on the A38 when her car collided head-on with a van. Rob Haring, headteacher at Hanley Castle High School, where Kelly was a pupil, said: "While we're not in a position to reveal what grades Kelly achieved, she was a more than able student who thoroughly enjoyed her subjects."

A memorial service will take place when the school reopens.