By Sean Coughlan
BBC News, at the ASCL conference
A-levels will disappear as a separate qualification in England if the new Diploma is a success, says the head of the exams watchdog.
Ken Boston said the Diplomas had not been explained well
Ken Boston, head of the Qualifications and Curriculum Authority, said a review of the A-level in five years could see its removal as a stand-alone exam.
Dr Boston urged school and college leaders at a conference to support the principles behind the Diploma.
But he agreed there were "extraordinary difficulties" in introducing it.
Dr Boston was taking part in a debate about the future of the Diploma at the annual conference of the Association of School and College Leaders, in Brighton.
Head teachers have been warning the government about the practical difficulties in implementing the new qualification ¿ particularly when it is meant to run alongside the existing A-levels and GCSEs.
But Dr Boston said that heads must not "lose their resolve" in recognising the value of the proposed changes.
He told the conference that the drive for Diplomas had originated within the "education community" and that the "unlikely revolutionaries" in the school system should not be overwhelmed by the practical difficulties.
"Such challenges are what leadership is about," he told the conference.
And he rejected the idea that the new structure was over-complex.
"Frankly, we haven't explained it. It just hasn't been communicated."
And he promised that once the idea had been "stripped down to the chassis" that pupils and teachers would be less daunted.
Head teachers have warned that it is untenable to expect schools to offer two separate, competing exam systems.
The future of A-levels is to be reviewed in 2013 and Dr Boston said that if by then Diplomas had been successfully established, then there would no longer be any function for a parallel A-level system.
A-levels would have "no utility" outside the Diploma structure, he said.
The ASCL general secretary, John Dunford, said this endorsed the head teachers' call for a Diploma that would provide an over-arching structure which could include A-levels and GCSEs.
Debating with Dr Boston was Alan Smithers from the University of Buckingham, who argued that the case for the Diploma in its proposed form remained unproven.
And he warned that if the structure of the Diploma seemed confused it could reflect an inherent confusion in its intended direction.
Professor Smithers also pointed to the logistical difficulties in setting up the qualification, including the requirement for work experience.
"I doubt if there's enough work experience to go round," he told head teachers.
'Wait and see'
Dr Dunford said he also shared these concerns about providing work experience, particularly over its quality.
Head teachers at the conference have reflected concerns about the complexity and the viability of the plans to introduce Diplomas.
They have also spoken of a "wait and see" approach, with a reluctance to commit themselves or their students to an exam system which remains of uncertain currency, compared to the well established A-levels and GCSEs.
When pupils and parents can "vote with their feet" over the new exams, there is also a concern that the Diplomas will become relegated to a second-tier status, with academic prestige remaining with the A-levels.
And Dr Dunford, who has been lobbying the government to amend the Diploma plans, concluded that there was a shift towards accepting the idea of a Diploma that would embrace rather than replace A-levels - as originally proposed by Sir Mike Tomlinson.
As Ken Boston told head teachers: "We're all neo-Toms now."