It has been in development since 2003, and its origins go back even further than that - arguably to 1990. For years, it was seen as the future of secondary education in England.
This month, the previous government's Diploma qualification officially comes of age, as the first set of results are announced for 16- and 18-year-olds who have taken its innovative work-related courses for the full two years.
But whatever the outcome, it is likely to be a bitter-sweet moment. The Diploma's future is more uncertain than ever, as the Coalition seems to lack enthusiasm for it. What are the prospects for this qualification now, and the broader debate about academic versus work-related learning?
The thinking behind the Diploma, the Labour government's high-profile attempt to accommodate both academic and vocational learning, can be traced back to a document published 20 years ago.
The Institute for Public Policy Research pamphlet, entitled A British 'Baccalaureate' and including a young David Miliband among its six authors, argued for a unified system, bridging the gap between academic A-levels and vocational offerings such as BTEC Awards. This, the pamphlet suggested, wrongly divided "academic" students from the rest and helped explain the low numbers of pupils in post-16 education.
Fast-forward to 2002, and a problematic set of reforms to A-levels prompted Labour to look again at the baccalaureate model. As education secretary, Charles Clarke set up a task force led by Sir Mike Tomlinson, a former chief schools inspector, to advise on creating an overarching qualification that would include both vocational and academic courses. In 2004, Sir Mike proposed a system incorporating GCSEs, A-levels and vocational courses.
However, in 2005 the government rejected this recommendation: Tony Blair decided that the public would not accept the "scrapping" of existing exams, and that GCSEs and A-levels would run alongside new, work-related Diploma courses.
Despite fears that this would perpetuate the academic-vocational divide, the government, backed by many employers, put huge effort into the Diploma. The concept was that it would offer not a single subject-based course, but a rounded curriculum, with independent thinking, team work, oral skills and project management to the fore.
In 2008, around 12,000 pupils began Diploma courses in one of five subjects. The TES has been told to expect up to 8,000 to receive their grades later this month.
The numbers have fallen far short of expectations: initial predictions were for 50,000 learners by September 2008. Even by September 2009, with pupils having embarked on courses to finish this summer and in 2011, only 36,000 were enrolled.
Nevertheless, so far the Diploma seems to have impressed those students and teachers who have experienced it. An evaluation of the qualification's first year by the National Foundation for Educational Research (NFER) found that 79 per cent of Year 10 pupils, and 76 per cent of Year 12s, were satisfied with their Diploma experience, with around one in four "very satisfied".
Three-quarters said they would consider recommending the courses to others. Students said they particularly valued the hands-on learning experience, and the chance to take part in, for example, workplace visits and work in teams.
However, the Diploma has faced many problems. One, perhaps surprisingly for those who might dismiss any work-related qualification as unchallenging, has been that it has been perceived as hard to pass.
To obtain a Diploma, candidates must pass not only the main parts of the qualification, but new "functional skills" tests assessing their capabilities in literacy, numeracy and ICT. This has proved challenging.
One source who has been involved with supporting functional skills tests said: "The Diploma is by far and away the best qualification on offer, because you end up with a more rounded, enthusiastic person.
"But I'm disappointed that numbers have not been higher. My feeling is that people have the impression that it's a hard qualification to pass. Functional skills is not an easy subject at all. It's rigorous.
"Schools are not putting candidates in for the Diploma because they are far too worried about their league table positions."
Concerns about the functional skills tests were echoed in the NFER report. There was "general concern", it said, that the tests were set above the average ability level of those taking Diploma courses. The courses were originally supposed to be benchmarked as equivalent to a grade C at GCSE, yet one teacher told researchers that passing them was closer to a grade B.
At one point, functional skills tests were proposed as a compulsory hurdle for the GCSE, although this plan has been dropped, while their introduction into apprenticeships has also been postponed.
One teacher involved with a group of schools and colleges' Diploma efforts in the South East said competition between schools made some heads reluctant to start Diplomas. The qualification often means sending pupils away from their "home" school to other institutions two days a week.
The teacher said: "The view of some heads here is that, 'I will have less grip on them and I cannot push them over the hurdle of five A*-Cs including English and maths.' This... deterred heads from going particularly heavily for the Diplomas."
Indeed, The TES has learnt that the last government was advised not to include the compulsory functional skills hurdle as part of the Diplomas for this reason.
A task force of exams experts led by Mike Cresswell, then director-general of the AQA board, said in a 2007 paper that the hurdle should be dropped after modelling the likely effect on pass rates.
Looking at the pass rate for a BTEC course in health and social care, they found this would collapse from 97 per cent to 2 per cent if it was conditional on pupils gaining C grades in GCSE English, maths and ICT. However, the Qualifications and Curriculum Development Agency insisted that the requirement stayed.
The Diploma's complexity has been a key problem. One exam board source described it as a "nightmare of a complicated qualification to deliver". Schools and colleges have had to work together, with pupils and teachers travelling away from their "home" institution for parts of a course. A Diploma can also include components from multiple exam boards (see box).
Caution among schools has depressed take-up. Malcolm Trobe, policy director at the Association of School and College Leaders, said he did not expect a significant rise in numbers this year, as many heads had been waiting to see how a Conservative government would view the Diplomas.
The worry for Diploma supporters, then, is a string of announcements from Sanctuary Buildings since May. The new Government has cancelled "academic" Diplomas due to start next year, scrapped the "extended" Diploma, which would have been worth 4.5 A-levels, and abandoned the requirement that Diplomas be offered to all pupils in 14 subjects and three levels by 2013. It has also cancelled an approval process which subjected joint bids by schools, colleges, employers and local authorities to quality checks.
Diplomas are relatively expensive - so far, schools and colleges have received an extra #163;1,000 per student. This subsidy's future after the next academic year is unclear.
All this caused one long-time supporter of the qualification, when asked for views on its current state, to reply: "The late, lamented Diploma. Oh dear."
The Government insists pupils should not be put off. Schools minister Nick Gibb has said: "We want to see how Diplomas work, and learn from them to improve the quality of vocational education."
However, even Sir Mike Tomlinson, the architect of the original plans and from 2007 to 2010 a "champion" of the Diploma, told The TES: "There remain some significant weaknesses in the Diplomas as they are currently formulated."
There were two problems, he said. The first was that Diploma students did not have to complete work experience specific to the subject they were studying. The second was recurring worries over content: for example, managers at the new technical colleges thought the engineering Diplomas "are not dealing with the aspects of engineering that they think should be there".
But he added: "The positive thing is that the Diplomas have been designed with significant input from employers and should give young people a clear progression route, from one level to the next. This is not always the case with other qualifications. Anecdotally, also, heads and teachers say the Diploma's content has been highly motivational to students."
Mr Trobe said: "The Diplomas suit the needs of some young people, for whom applied learning really does suit. There are some very big success stories out there.
"The crucial factor now will be employers. If they start picking up youngsters who have done Diplomas, that will be a great help. But the Diplomas are very much on a knife-edge at the moment."
Sir Mike believes that Diplomas will endure, if only where schools, colleges and employers see a role for them.
He said: "Whether it will ever be the sort of qualification that was initially envisaged, I don't know. One thing is for certain: it will not replace A-levels."
Not everyone is convinced. Chris Healy, head of Balcarras School in Cheltenham, a long-time Diploma sceptic, said: "I am delighted that the Government has withdrawn its total support for Diplomas. I think they will decline quite rapidly now, because I don't think there's any genuine desire or need for them."
With concern about the split between vocational and academic education an abiding theme, and the Diplomas facing uncertainty, many will wonder if this question will be revisited yet again in coming years.
Senior exam board figures were so worried about the complexity of grading the Diploma that they wrote to the then education secretary, Ed Balls, asking for clarity, The TES has learnt.
They were unhappy at the prospect of awarding grades without full control over the process leading to final decisions.
Although one awarding body decides the overall grade for each pupil's Diploma, components can be taken with other boards.
In addition, two central parts of the Diploma - work experience and personal, learning and thinking skills - are assessed by the candidate's school or college. The TES understands that concerns came to a head as the boards were due to sign a contract for Diploma grading work.
A source close to events said boards were "reluctant to sign because if there were any cock-ups, they would be liable, but they would be liable for other people's operations, over which they had no control whatsoever."
The boards are also believed to have been unhappy about the influence wielded over the Diploma by the Government and the Qualifications and Curriculum Development Agency, pointing out that the boards would be in the firing line if things went wrong.
In January, the Government wrote to schools and colleges telling them that they were accountable for ensuring pupils completed all parts of their diploma.