They are "the biggest development in examinations anywhere in the world".
Ministers wanted to make Diplomas more appealing to universities
More than that, as the first major qualification and curriculum reform ever designed to be "led by employers", they are unique.
This description of the new Diplomas, due to start in England in just nine months' time, came from Ken Boston, the government's chief qualifications and curriculum advisor.
He was, appropriately, addressing the National Educational Business Partnership (NEBP) Network conference, the body that acts as a dating agency between employers and schools.
And, judging by the latest progress report on the Diplomas from the National Audit Office (NAO), the importance of that message still needs a lot of reinforcing with employers.
Because in its report on preparation for the Diplomas, the NAO concluded this week that the low level of involvement of employers is one of the biggest threats to the success of the new qualifications.
Specifically it warns that "engaging employers is the least developed aspect of most partnerships".
All these local partnerships of schools, colleges and education authorities are supposed to involve employers in developing their plans for education for 14 to 19-year-olds.
Yet the NAO says 45% of them have not yet done so.
Why does it matter? Well, in purely practical terms, it matters because work placements with businesses are essential to the Diplomas.
The NAO says two-thirds of the partnerships had encountered difficulties arranging the required 10 days of work experience.
But more fundamentally, the Diplomas are supposed to be "employer-led qualifications".
Work-related learning is meant to be at the heart of the new curriculum and the Diplomas are meant to bridge academic and practical learning.
'In the dark'
Amid all the concern that the Diplomas could, in Alan Johnson's words, "go horribly wrong", this unique role for employers has been rather overlooked.
What role did businesses have in the creation of O and A-levels? None. They were the preserve of the universities.
Even when GCSEs were created two decades ago, employers had little influence.
Yet, as the Leitch Report highlighted, skill levels in the UK workforce are just not good enough.
So, finally, employers have been given the keys to the secret garden of curriculum reform. But will they use them?
Certainly, the big hope for Diplomas is that an industry-verified curriculum will appeal to youngsters who have been put off by the traditional academic curriculum and that the emphasis on applied learning will produce a more skilled workforce.
But there are two big concerns.
First, as identified by the NAO, while some big companies have certainly thrown themselves into Diploma design, many smaller businesses remain largely unaware of what they involve.
The second worry is that, out of a concern to ensure that the Diplomas are acceptable to universities, the government is making them more academic in content than employers really want.
On the first score, concerns were raised at the NEBP Network conference that small and medium businesses, in particular, have not become involved in Diploma development.
Indeed, it was claimed that many small businesses - like most parents and students for that matter - remain in the dark about the Diplomas, even though the first five start next September and a quarter of 14 to 19-year-olds are expected to take Diplomas by 2013.
Moreover, there were complaints that a lack of funding is making it difficult for local Education Business Partnerships to act as effective brokers between schools and businesses.
This matters because employers are just as essential to the delivery of Diplomas as they are to their design.
Schools and colleges need the support of local businesses for work-related learning in areas such as engineering, manufacturing and product design, travel and tourism and retail.
Thus there is a real danger that when the first young people arrive clutching their Diploma certificates, they will either be met by bafflement from many prospective employers or will have followed a curriculum the employers do not recognise or support. That will not encourage others to follow.
The second risk to the Diplomas has arisen from an understandable concern in government to avoid yet another vocational qualification reform being labelled as second-class.
That is why the government insists the Diplomas are "academic", not vocational, practical or even "specialist" qualifications.
Ministers have worked hard to get elite universities to support the Diplomas as a route into higher education.
And, going a step further in the academic direction, they recently announced three new Diplomas in non-vocational subjects: sciences, languages and humanities.
This seems a strange move. After all, a key aspect of the Diplomas is that they can be combined with academic subjects.
So students could, for example, take a Diploma in business or engineering, combined with A-levels in economics or maths.
So why dilute the message that Diplomas are about work-related learning?
Yes, it is true that employers do not want "oven-ready workers". They still expect to train their new employees.
But if the Diplomas are to be more useful to them than GCSEs and A-levels alone, then surely they must contain a large element of applied learning and work-related experience?
The head of the Enterprise Business Unit at Vodafone, Kyle Whitehill, probably spoke for many employers when he told a conference that "the two most important skills in the workplace are interpersonal skills and presentational skills".
He did not, please note, prioritise acquisition of academic knowledge or evidence of the ability to memorise large slabs of information.
No-one is saying the Diplomas should be about narrowly focused, job specific skills.
But if the employers are not fully involved, and if the Diplomas veer too far towards academic learning, they will fail to be significantly different from what is already on offer.
After so many previous failures in vocational qualifications, the Diplomas cannot afford to fail.
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