The exam boards were this week insisting that the first fall in the proportion of students gaining higher grades in English and maths GCSE was not evidence of any slide in standards in schools.

The reversal of the trend of year-on-year improvements in exam results was being put down to greater numbers of weaker students sitting English and slightly poorer performance overall from maths candidates.

Ministers made no attempt to explain the 1.3 per cent drop from last year in the proportion of English students gaining GCSE grades A* to C or the similar 1.1 per cent fall in the proportion of maths candidates achieving higher grades. This year, 56.9 per cent of candidates achieved grade C or higher in English, compared with 58.2 per cent last year. In maths, 44.8 per cent of candidates achieved the higher grades, compared with 45.9 per cent in 1993.

Lord Henley, one of the junior ministers at the Department for Education and Employment, acknowledged the drop in the proportion gaining higher grades, but pointed to the fact that the actual numbers with good results had gone up.

He said: “Although there was a small drop in the proportion of higher grades achieved in maths and English this year, these are still excellent results in these core subjects. The number gaining these higher grades increased again. ”

Overall, the results show that the proportion achieving higher grades has improved in all other subjects. In science, 47.5 per cent of candidates achieved grade C or higher. The 1.7 per cent improvement over last year may be due to the switch away from the separate sciences of physics, chemistry and biology in selective schools.

According to the Joint Council for the GCSE, which represents all the exam boards, the surprising English results may be due to teachers entering weaker students for the exam.

In the aftermath of the Government’s decision to ban English exams assessed totally by coursework, the numbers taking the exam fell and the proportion achieving higher grades increased.

“We saw a 5 per cent decline in the entry for English last year, which was contrary to the growth in the number of fifth-formers. It may have been that teachers did not enter weaker pupils for a exam where timed written papers accounted for a minimum of 60 per cent of the marks. Having seen the exam, they have entered a wider ability range this year,” said John Edmundson, the board’s secretary.

Entries for all subjects increased this year. However, the number of English candidates increased by 8.4 per cent, more than double the 3.6 per cent increase in maths.

The results are likely to confirm the belief of many English teachers that the drastic reduction in coursework is having an impact. Anne Barnes, general secretary of the National Association for the Teaching of English, said the switch to mainly written exams did not allow students to show what they can do.

“The changes are bound to depress marks, particularly around grades C and D, where you find the bulk of candidates. I suspect that the reduction in coursework - and the consequent fall-off in private reading - will have an adverse effect on next year’s A level results,” she said.

The exam boards appeared confident the English and maths results were not due to harder papers than usual or more stringent marking. Sir Ron Dearing, chairman of the School Curriculum and Assessment Authority, conducted an inquiry last year into what had appeared to be generous awarding of grade B by two exam boards, but the boards believe consistency has been achieved this year.

There appears to have been a slightly poorer performance overall in maths than in previous years, but the exam boards say a slight decline in one year cannot be viewed as significant.

“We are talking about a very fine border line and this degree of variance might be the result of one or two marks,” said Mr Edmundson.

Other experts suggested the results could have been depressed because teachers have had to cope with changes in the maths curriculum. Coursework in maths has also been restricted to a maximum of 20 per cent, but that took effect for last year’s exam takers .

The Labour party claimed this year’s exam takers had been the victims of Government turmoil. David Blunkett, the education spokesman, said: “Five years of Tory reforms by successive secretaries of state have taken their toll. Where we should have seen a dramatic increase towards national exam targets and beginning to match our global competitors, instead we have the aftermath of the demoralisation and disruption caused by the constant changes in the national curriculum and the dispute over testing.”

He also pointed to the fact that there has been a fall in the number of qualified maths and English teachers. Between 1984 and 1992 the number of qualified maths teachers fell from 30,000 to 23,500 and the number of qualified English teachers fell from 30,800 to 22,400.

Lord Henley congratulated students and teachers for a magnificent effort. The results showed, he said, a slight improvement in the proportion of students gaining higher grades. The proportion gaining the top starred A grade had gone up 0.3 per cent to 3.2 per cent.

The number of GCSE entries rose overall by 10.3 per cent - a larger increase than the increase in the number of 15-year-olds. The national curriculum has meant an increase in the numbers taking technology. This year there were 350,000 entries and 44 per cent gained grade C or better.