The head of the exams watchdog also thinks a diploma may happen

The Commons education committee said the government should keep the idea under review.

It said many felt disappointed ministers had decided to keep GCSEs and A-levels, in their response to the Tomlinson report on 14 to 19 learning.

But the committee said everyone should support the proposed diploma for vocational studies.

Confidence

Committee chairman, Labour MP Barry Sheerman, said: "The government has been criticised for failing to implement Tomlinson in full, but implementation was always going to be fraught with difficulty.

"To have set out to bring in the unified diploma but to have failed could have seriously damaged confidence in the education system.

To have set out to bring in the unified diploma but to have failed could have seriously damaged confidence in the education system Barry Sheerman MP

"We did agree, though, that the question of integration of GCSEs, A-levels and vocational qualifications within a unified diploma should be kept under review."

The committee welcomed other aspects of the government's plans, for instance for educational maintenance allowances to encourage youngsters to stay in education beyond the age of 16.

But it said that if the government wanted collaboration between various local providers in delivering the curriculum to 14 to 19-year-olds, it would have to address more quickly differential funding.

Colleges complain there is a gap of at least 9% between what schools get and what they get.

'Green light'

"The logic of establishing a unified 14 to 19 curriculum is that it should be supported by a unified 14 to 19 funding methodology," the select committee said.

Meanwhile the chief executive of the Qualifications and Curriculum Authority, Ken Boston, has said he was also disappointed the advice of his board was not taken in full by the education secretary.

This had been that the Tomlinson reforms formed a coherent package which should not be implemented piecemeal.

But he said the critical point was that the government had now "given the green light" to the development of a diploma structure.

"Our advice was that the general qualifications should remain until 'something even better' can be introduced.

"We now have the opportunity and the breathing space to develop it," he said.

Parental input

Its general components must be as robust as A-levels, and verified by universities.

Its vocational components must be similarly as robust, and verified by industry.

"In matters of qualifications reform, governments tend to follow rather than lead," Dr Boston said.

In matters of qualifications reform, governments tend to follow rather than lead Ken Boston QCA

"It will be ultimately the demand-side coalition of learners, industry and universities - together with parents and teachers - which will determine whether A-levels remain and for how long, and whether the National Diploma succeeds or fails."

"If all of us who believe in this reform are successful, the question in 10 years' time will not be 'Why would you bring the A-levels and the Diploma together?'