Ministers will be prevented from "dumbing down" exams to suit their own political purposes under major concessions offered by government to its latest education bill.
A series of changes that should limit the scope for ministerial "meddling" in the qualifications system were expected to be passed by the House of Lords this week.
The Apprenticeships, Skills, Children and Learning Bill would, ministers claimed, "provide for Ofqual to be a genuinely independent regulator" when it is introduced. But, controversially, it also allowed them to intervene and set the minimum requirements for specific qualifications.
Now the Government, fast running out of parliamentary time to get the legislation through, has offered changes that will curtail that power.
Ministers will only be able to set requirements for a qualification where it is necessary to ensure the pupils taking it are studying a curriculum appropriate for their age.
Baroness Walmsley, the Liberal Democrat peer who played a major part in wringing the concession out of government, said it would help to prevent ministers using the power for political rather than educational reasons.
The concessions will also allow Ofqual to ignore the minimum standards if they are not consistent with those set for comparable existing qualifications, in a change aimed at preventing political "dumbing down".
"There has always been the suspicion that successive governments have wanted to demonstrate the success of their policies by increasing exam results and this should help prevent that from happening," Baroness Walmsley said.
The Government amendment would also force a secretary of state to lay any minimum qualification standards they proposed before Parliament.
But the Lib Dems were this week confident that they could gain an even bigger concession that would ensure any such standards were actually debated and voted on by Parliament.
Baroness Walmsley said: "The Government has set up the Qualifications and Curriculum Development Agency to advise on the curriculum, and Ofqual to ensure it is properly assessed.
"So you have got this great system, but the bill would have allowed the secretary of state to come in on his own and specify a requirement for political reasons.
"You don't buy a dog and then bark yourself. Ofqual will not have public confidence if ministers can interefere like this."
Other changes offered by government will mean the Ofqual board, rather than the secretary of state, appoints the deputy chair of Ofqual and that, in normal circumstances, ministers will have to consult the chair of Ofqual before appointing its board members.
But a loophole, which the Lib Dems were hoping to close, would allow this consultation to be skipped if it is "not practicable".
Ofqual is now also likely to see its proposed controversial power to cap exam fees limited to where it has concerns about value for money. And reviews of capping decisions would have to be carried out by someone independent of Ofqual under a further government concession.