Just over a year ago, everyone thought they knew where they stood. Much of the academic research said that the qualifications being promoted through the Train to Gain service offered no real benefits, and the Government found it hard to give training away.
Now the scheme has gone from a Pounds 200 million underspend to demand that cannot be met even with a budget of more than Pounds 900m. And the debate about the value of the qualifications it offers is about to be reopened.
In the blue corner are the Conservatives. Their pitch for the next general election includes plans to overhaul Train to Gain. They plan to divert money away from the level 2 national vocational qualifications - which they maintain are mostly a waste of time - in favour of apprenticeships.
In the red corner, new research for the Government may yet show that the qualifications that formed the bulk of Train to Gain work have demonstrated real benefits for more people than was previously realised.
The UK Commission for Employment and Skills (UKCES), a government advisory body set up to help reach the ambition of world-class skill levels in the UK, is shortly to publish a review of research into the relative benefits of qualifications. It is expected to challenge the gloomy picture of Train to Gain's focus on intermediate skills through NVQs.
The debate matters because the result is likely to determine how the bulk of adult education funding is spent as we move closer to 2020, the deadline set by Lord Leitch for the UK to become a world leader in skills. Then the country will see how it measures up against the rest of the world.
Until recently, much of the research suggested that an NVQ level 2 - rated as equivalent to GCSE but largely earned through accrediting skills which may already have been learnt in the workplace - was almost worthless. Several studies showed that the qualification did not help students increase their lifetime earnings, and some were even likely to damage their prospects by spending time achieving the qualification.
Alison Wolf, professor of public sector management at King's College London, has angered the Department for Innovation, Universities and Skills, over the two years of its existence, by highlighting evidence that its flagship training scheme was promoting certificates of no real value.
Of Train to Gain's approach to funding NVQs, she said: "It's a complete and total waste of money, flying in the face of all the evidence that it is just accrediting skills people already have.
"All this has shown is that what turns out to be valuable are the things that parents or families would choose, as opposed to government ministers or academic researchers."
Studies dating back to at least 2002 had been unable to show any evidence of people who had achieved intermediate-level NVQs earning more than their counterparts who did not have them, even among students who had no prior qualifications at all.
Other research suggested that progression to higher-level qualifications was rare for people who achieved NVQs; these tended to be stopping points that marked their final level of achievement.
By contrast, the returns for apprenticeships have been proven. It was noted in the 2007 research report A Cost-Benefit Analysis of Apprenticeships and Other Vocational Qualifications, written for the then Department for Education and Skills, that apprentices were a group selected by employers and, therefore, likely to have higher natural ability. However, the returns were real, were increasing and were greater than for other vocational qualifications.
"These wage benefits, as an indicator of the future productivity of apprentices, dwarf any costs incurred by the state and employers," concluded the report by Steven McIntosh, of the University of Sheffield.
But even as the Government increased the flexibility of Train to Gain, opening up the potential to fund higher-level qualifications that were thought to offer greater benefits, it did not accept that level 2 NVQs were worthless in the workplace. Research released in October provided some of the first evidence that its key strategy of focusing on these qualifications brought real benefits for some students.
A paper by Augustin de Coulon and Anna Vignoles of the London School of Economics in October found that for women, at least, NVQ level 2 could mean an increase in wages similar to that found with other qualifications at that level. Women with lower prior qualifications were likely to benefit the most.
The forthcoming UKCES research, which revisits earlier data to look more closely at specific groups, is also expected to show previously hidden benefits of NVQs.
Perhaps worryingly for the Tories, the person responsible for this study is the very man who produced some of the earlier research which they say helped to form the thinking behind their skills green paper, their main statement of intent as far as further education is concerned.
Dr McIntosh, a reader in economics, is reluctant to be drawn into a political battle but does say he is "not a Conservative". He declined to comment on the Tory proposals, but said his earlier research was "probably a bit outdated to base a policy on".
Apprenticeships offer big returns - "I had to check the figures a few times," Dr McIntosh said - but that could be partly explained by employers taking their pick of candidates for a relatively small number of places, he said. NVQs, on the other hand, could offer more people the chance to progress. "It could be that they are more of a stepping stone," he said.
But other academics say there is no point trying to cherry-pick groups in the hope of finding some who are receiving demonstrable benefits from taking an NVQ level 2 when most do not.
Professor Wolf said: "Obviously, somewhere in the system people are managing to get qualifications that do them some good. But nevertheless it's a completely misguided policy and it's time to give it up."
David Willetts, the shadow secretary for skills, said the Conservatives would not ditch the Train to Gain scheme. However, under their plans, its purpose would be changed out of recognition into a vehicle for recruiting Pounds 770m worth of additional apprenticeships.
Mr Willetts said he did not accept the argument that NVQs achieved through Train to Gain had encouraged people to progress to higher-level qualifications.
"There isn't the evidence at the moment that Train to Gain helps people with progression from level 2 in the way which is claimed for it," he said. "There are figures of all the people who do Train to Gain and then get promoted, but it could just as easily be that we find that when people are thinking of promoting someone, they tend to put them on to Train to Gain."
With apprenticeships to the fore, they too are likely to get a rebranding if the Tories win power. Mr Willetts has drawn a distinction between "real" apprenticeships - employer-based and at level 3 - and the rest of current apprenticeships.
Level 2 apprenticeships are expected to be described as some form of "pre- apprenticeship training", almost returning to the situation when Modern Apprenticeships were launched.
"We haven't renamed GCSEs as A-levels; we keep the distinction between level 2 and level 3. Why shouldn't we do the same for vocational qualifications?" Mr Willetts said.
Despite the emphasis he has placed on level 3 being a "real" apprenticeship, he declined to outline whether the Conservatives would let the higher-level qualifications grow at the expense of level 2.
Chris Humphries, chief executive of the UKCES, said that even though level 3 was likely to become the standard minimum level of qualification in the workplace, to make it so would be a mistake.
He thought the Conservatives had so far outlined a broad "headline" policy in promoting apprenticeships, particularly at level 3, and he believed they were well aware they would have to address a gap in their plans for the 30 per cent of adults with no qualifications.
Apprentice numbers are acknowledged to be harder to increase because they depend on employers wanting to recruit. They also have relatively high entry requirements, creating the need for some alternative provision for unskilled adults.
Mr Humphries defended the current approach of Train to Gain, despite criticism that it mainly accredits pre-existing skills and does nothing to boost productivity. With the greatest challenge for increasing the UK's level of skills being in reaching the over-25s, he suggested that Train to Gain offered a way to getting them back in touch with the education system, making them realise that their skills could earn them qualifications and providing a base from which they could reach more valuable level 3 awards.
Mr Humphries said: "If you look at Labour's policy over the last 10 years, progress has been greater than at any time since the Second World War in terms of changing skills levels. But we were starting from a very low point.
"What we can't afford as a nation is to have a limited number of people reaching level 3 only for it to mean fewer people reaching level 2. That would risk creating a long-term and perhaps permanent underclass of adults who never get to level 2 and are never going to have a proper opportunity in the labour market."