Vince Cable released the latest stats on apprenticeships in England today, which show that more than half a million people began a placement in 2011/12.

Understandably, it’s being presented by the government as a good news story. The coalition smashed its initial target of 50,000 more apprenticeship starts in 2010/11, and the latest figures prove that numbers have almost doubled in the last two years.

All three main parties support apprenticeships. Today the Labour leader, Ed Miliband, announced that he would oversee the creation of 33,000 more off the back of the HS2 high speed rail project, if elected.

So what’s the small print?

More people are starting apprentices than ever, but success rates have gone down.

Today’s statistical release shows that only 73.8 per cent of apprentices actually finished their placement in 2011/12, a decrease of 2.6 percentage points from the year before.

Success rates had previously been rising year-on-year since 2007, but they fell across all age groups for the first time last year.

A bigger cause for concern is the fact that the average apprentice is getting older and fewer teenagers are signing up.

Most of the big rise in the total number of apprenticeships is driven by huge increases in the “over-25s” category, as this graphic shows.

To put this in perspective, 44 per cent of people who began apprenticeships last year were aged 25 or over. Three years earlier only 23 per cent were in the oldest category.

Over-25s are now the biggest age group, and this category is growing much faster than any other.

For the first time, the 2011/12 figures show a fall in the number of 16 to 18-year-olds signing up – a 1.4 per cent drop to 129,900.

This is a worrying trend - for two reasons.

First, it suggests that apprenticeships may not be the answer to the persistent problem of youth unemployment, as the coalition has suggested in the past.

It may be significant that Vince Cable didn’t mention youth unemployment today, or joblessness at all. Instead, he talked about making up for a skills shortage in the job market.

Second, BIS research suggests that almost half of over-25s who do apprenticeships would have got the same kind of training anyway if the government had not intervened.

BIS statisticians found in a report last year that the ”deadweight” – where the state ends up paying for something that would have happened anyway – was far more marked among older apprenticeships than teenagers.

As many as 44 per cent of over-25s would have been trained anyway,  even if the government wasn’t offering to meet up to 50 per of the cost.

The implication is that employers are just shifting the cost of training to the government, meaning that millions of pounds of taxpayers’ money are effectively being wasted.

If the age profile of the average apprentice is going up, the proportion of wasted spending is probably going up too. This is not something Mr Cable enlarged upon in his interviews with the media today.

Quality or quantity?

We know that government spending on apprenticeships has increased, from just over £1bn in 2009/10 to nearly £1.4bn last year.

But the numbers of apprenticeships are going three times more quickly than the amount of money available to pay for them.

The obvious conclusion is that we are spending less on the average apprenticeship, which suggests that as the numbers go up, they are getting shorter.

We have known for years that not all apprenticeships are created equally. Last year the National Apprenticeship Service reviewed 87 cases where apprenticeships were being delivered in less than six months and failed to meet official quality benchmarks.

Last year the National Audit Office found that in 2008/09, 12 per cent of placements took six months or less, rising to 19 per cent in 2010/11.

But in these latest figures a few months spent learning how to stack shelves and a three-and-a-half-year stint at Rolls-Royce both count as the same.

In fairness, the government has made some effort to improve duration and quality.

Last year a minimum length of 12 months was introduced. But that was only for 16-18-year-olds, and it only came in after these latest stats were compiled.

A BIS spokesman told us there have been repeated interventions to improve quality in recent years, including a crackdown on employers who only took on apprentices for short stints over slack holiday periods like Christmas.

Update: Business minister Matthew Hancock asks us to point out that the government scrapped so-called Programme-Led Apprenticeships (where people were trained in colleges and not paid, rather than attached to an employer) in 2011 because of concerns about quality). These made up 21 per cent of apprenticeships among 16 to 18-year-olds in 2009/10. He says: “To improve quality you have to remove some poor provision, and to make more rigorous you have to make harder to succeed. So the rapid growth while we do those things is impressive, and the provision we shut down due to not having jobs attached more than offsets the decline in numbers for 16-19s.”

By Patrick Worrall