Further uncertainty surrounded proposals for new diplomas for English students this week after Mike Tomlinson, who drew up the plans, said they were not compatible with league tables.

Charles Clarke, the Education Secretary, told MPs last month that exam results for every school would still be published, at ages 16 and 19, under any new system.

But this week, Mr Tomlinson told a Duke of Edinburgh Award conference that, while, some form of accountability was needed for the diploma, it would not lend itself to measurement through league tables.

The first problem was that pupils would take the qualifications when they were ready, rather than at a fixed age, making it dificult to compare performance.

He said: “If students move through at their own pace I think you have to conclude that the present form of the tables cannot be sustained.

“There has to be a political will to do something about that. We will have to wait and see what they say about that.”

Ministers’ reluctance to countenance such changes will fuel speculation that they are unlikely to agree to implement fully Tomlinson’s proposals when they respond to them in the new year. The former chief inspector, who led an 18-month inquiry, has proposed a four-level diploma to absorb GCSEs, A-levels and vocational qualifications by 2014.

Mr Tomlinson told the conference in Liverpool he had been persuaded to shy away from making “wider activities”, such as Duke of Edinburgh award, art and sport, a compulsory part of the diploma.

Including them was not possible until all pupils had access to these activities. He was also concerned that pupils caring for relatives would not have time to do extra-curricular work.

Instead wider activities will be an entitlement and Mr Tomlinson said that he hoped that when all pupils had access to such activities they should be compulsory.

Mr Tomlinson said: “What we’ve got to understand is that there are different ways of people achieving, different things they achieve. What we need is a system that recognises that. For some young people their achievements outside of school are much greater than those in school.”

But Steve Sharp, operations director of the Duke of Edinburgh scheme, fears extra-curricular activities may be sidelined as politicians prioritise the rest of Tomlinson’s reforms.

“My argument is there is not perfect A-level teaching in all parts of the country but it doesn’t mean children aren’t expected to do them,” he said.

“So I am in more of a hurry than him to make these activities compulsory.”