Details of a new examination regime to replace GCSEs are to be announced in the biggest overhaul of secondary school testing for a generation.
Education Secretary Michael Gove and Deputy Prime Minister Nick Clegg, who clashed openly earlier this year, will launch the reforms jointly after negotiating a plan agreeable to both sides of the coalition.
The changes, which apply only to England, are designed to introduce more academic rigour to exams for 15 and 16-year-olds amid concerns about falling standards and dumbing down since the introduction of GCSEs in the late 1980s.
That will mean an end to modular and rolling assessments and a stronger emphasis on the more traditional exam at the end of two years of study. There will also be a limit to the proportion of top grades that are awarded after years of ever-rising numbers of As and A*s.
However, after vociferous protests from Liberal Democrats including Mr Clegg there will be no return to the two-tier system of qualifications that pre-dated GCSEs, when the academically talented took O-levels and the rest sat CSEs. Additionally, the proposed implementation of the reforms has been pushed back until autumn 2015, after the next general election, meaning an incoming Labour government could potentially repeal the changes before they were implemented. Labour has not as yet indicated that it will oppose the plans, although it criticised the timing and the leaking of details to the press.
The issue has strained coalition relations after Mr Gove's plans for a return to an O-level-style exam system were leaked in June without the foreknowledge of either Prime Minister David Cameron or Mr Clegg. The Lib Dems responded furiously to the leak, the Deputy Prime Minister saying at the time he was against "anything that would lead to a two-tier system where children at quite a young age are somehow cast on a scrapheap".
It is understood that Mr Gove and Mr Clegg have worked closely together over the summer to find common ground. A source said it had been a "really good coalition process" and that the end result would "raise the bar without shutting the door".
Former chief inspector of schools Sir Mike Tomlinson said he was generally "positive" about the proposals, but questions remained. He told the BBC Radio 4 Today programme: "The first, of course, is the obvious one - that the examination, whichever form it takes, should be available to a wide range of ability and should not, as has been worried about, marginalise some group of pupils. As a teacher I remember that system well... terribly difficult decisions had to be made as to whether you entered a student."
He went on: "I think the other question for me is that there are some subjects now available to students at GCSE which cannot... be tested simply by a three-hour examination; for example, art, for example, dance or music." Sir Mike warned there was an "obsession with continually fiddling" with the exam system, but said the latest round of changes could be an improvement. "I am very much in favour of having only one board able to set examinations in English or maths or the sciences rather than the number at the present."
Martin Johnson, deputy general secretary of the Association of Teachers and Lecturers, said: "Designing assessments and tests is highly technical and best left to professionals. A new exam certainly should not be designed on the back of a restaurant menu as a short-term political fix by ignorant ministers. This is an insult to the nation's children who will have to live with the consequences if the crackpot ideas are implemented. Since young people will have to stay in education and training until they are 18, there is growing opinion that we no longer need external testing of 16-year-olds."