The inquiry was ordered by the Education Secretary Gillian Shephard to establish whether steadily rising examination results were caused by easier papers.

After months of wrangling the investigating committee is believed to have concluded that examination standards at 16 and 18 have not dropped, but the knowledge required for A-levels, in particular, has become broader and less detailed - a trend it wants reversed.

Despite much infighting on the joint committee - made up of nominees from the School Curriculum and Assessment Authority and the Office for Standards in Education - its conclusions appear to have neatly defused a politically sensitive problem. Delays in reaching a consensus also mean it has been overtaken by events.

Some of the suggestions it makes on A-levels have already been addressed in the current revisions of the core curricula, which were made as a result of Sir Ron Dearing’s conclusions on 16-19 education - including a requirement for more classic literature to be made compulsory in English.

Other suggestions will be handed over to working committees of SCAA and its successor to implement.

Right-wingers who would have complained of a cover-up if no dilution of standards was found may be mollified by the report’s findings that examination demands have changed, while Labour will have little ammunition to blame falling standards on market-led policies in schools and examination boards.

Only one of six areas covered in the report - A-level English - appears to have been much revised since the production of a draft version in late summer. It is likely to come to much tougher conclusions, particularly on weaker candidates’ writing skills.

The chief inspector of schools, Chris Woodhead, is believed to have been most unhappy about the tone of the draft: he had expressed interest in an inquiry some time before Mrs Shephard took action.

One major problem for the committee in establishing whether syllabuses and marking have become less demanding and grade standards maintained since 1975 was the lack of evidence and, in particular, a dearth of completed examination scripts.

This, coupled with new requirements of candidates’ knowledge and changes from the O-level to GCSE, appears to have left the way open for arguments over interpretation, and the number of personnel changes on the inquiry and the time it has taken suggest a number of arguments en route.

Stories surfaced in August that “traditionalists” on the inquiry felt they were being pressured by ministers to produce a “whitewash” that would reject fundamental reforms of the examination system. This was rejected by Gillian Shephard, who said it would be difficult to whitewash a report she had never seen.

Maths A-level was the only area in the draft report where some diminution of standards was evident: the inquiry found significant changes in syllabus content, particularly in statistics where performance had improved. Mechanics standards remained broadly constant, but pure maths was less demanding, with a shift in performance at A and E grades.

There was also understood to be less emphasis on algebra, problem-solving and reasoning, with a corresponding impact on performance at the highest grades.

In the draft report, it is understood that English literature

A-level was not found to have changed fundamentally, although the demand made on students had altered in some ways. Writing skills at grade E were a persistent problem.

The draft is also believed to have found very small overall changes in chemistry A-level, although there was less factual content and more emphasis on comprehension.

GCSE performance in the same three subjects is also understood to have shown a change to emphasise breadth at the expense of depth. By and large, standards were broadly comparable, but in English at least there was some grade variation between syllabuses.