Today's pupils must perform just as well as students did in the late 1990s to get an A grade at A-level, a major review of standards in four popular subjects concluded this week.
The Qualifications and Curriculum Authority investigation will provide some comfort to teachers and students who face accusations every summer of dumbing down as A-level pass rates rise.
John Dunford, general secretary of the Association of School and College Leaders, said: "Let's hope that this report helps to stem the flow of negative comment in August each year. Things are not getting worse, they are getting better year on year."
But the reports also contained some disturbing findings for ministers by identifying which boards offered the best chance of high grade passes at A-level.
The review also highlighted continuing problems with maths A-level. And it appears to be slightly easier to get an E grade in some subjects than it was in the late 1990s, the review found.
The QCA reports investigated whether standards were being maintained in maths, French, sociology and computing between 1997 and 2004. Between them, these subjects have more than 100,000 entries annually.
For each of the subjects, review teams compared syllabuses from 1997, 1998 or 1999 with those of 2004, and up to 150 AS and A-level scripts from those years.
They compared the work of candidates who were awarded A grades in each year and did the same at E grade.
For each subject, it was found that the quality of work needed to get an A grade had not changed markedly.
At E grade, the situation was more complicated. In French, standards had fallen slightly, except in the case of scripts marked by the AQA board, which were better than those in 1997.
In sociology, it had become easier to get an E grade. In computing, standards were maintained for the AQA board and the Welsh WJEC, but fell quite dramatically among Edexcel candidates. In maths, E-grade students performed roughly as well in 2004 as in 1998, although the work of Edexcel students was better in 2004 than in 1997.
Mr Dunford said that no one had been able to demonstrate that there had been any fall in standards at A-level over recent years, even though pass rates have risen for 23 years in succession.
However, Ruth Lea, director of the Centre for Policy Studies and a persistent critic of standards, said that the QCA had a "huge vested interest" in saying that standards had been maintained.
Last month, the Nuffield Foundation found widespread concerns among university admissions tutors that students lacked basic English and maths skills and the ability to think for themselves.
The QCA report offered no comment on whether the Curriculum 2000 reforms, which broke all A-levels into six modules, had led to "dumbing down", as some admissions tutors say.
The report confirmed that standards vary between the boards. In French, students taking exams through the WJEC tended to perform less well at all grade boundaries than those taking other boards' exams.
The reviewers were scathing about WJEC students' work in the first year sixth-form, and said there was little evidence of progression beyond GCSE, especially in the oral exam. By contrast, AQA A-grade French students "demonstrated a high level of competence across the range of skills".
In A-level computing, Edexcel candidates were weaker at both A and E grades than their counterparts taking exams through other boards. In maths, OCR students showed the weakest performance for their grades, the report found.
* A MORI poll for the QCA of nearly 3,000 students, parents, pupils and members of the public found that trust in A-levels has been growing in recent years. Some 68 per cent of teachers said they had confidence in the A-level system.
Easiest and hardest boards for achieving A-grade at A-level (2004)
Maths Harder: Edexcel Comparable: AQA, CCEA, WJEC Easier: OCR
French. Harder:AQA. Comparable: CCEA, Edexcel, OCR. Easier: WJEC
Computing. Comparable: AQA, CCEA, OCR, WJEC. Easier: Edexcel. Sociology. Comparable: all boards.