With unemployment among 18 to 24 year-olds nudging a million, and all manner of statistics showing that social mobility is neither what it was nor what it should be (arguably), the question of how young people secure company internships and work experience has become a resonant one.

You will recall the issue became politically charged not that long ago, with messrs Cameron and Clegg not exactly speaking as one about whether it is unfair and economically harmful for employers to give work experience to the children of mates (PM and deputy disagree on interns).

Many of us may be hypocrites about this. On the one hand, any employer knows that fishing for talent in the broadest and deepest talent pool is best for his or her business.

On the other hand, it is hard to resist the pleadings of old friends or business associates, desperate for their kids to be doing something a bit more productive than exchanging not-so-profound reflections about the world on Facebook when not studying.

And, of course, the lazy propensity in all of us encourages us to bring into our own work environments the children from the backgrounds and families we know, rather than someone whose credentials are only on paper.

So I was intrigued by an email from a London-based charity, which was forwarded to me by an outraged well-heeled parent.

Many people will be shocked by the idea that money can so directly and crudely secure possible career advantage for the children of the rich

This charity has taken the ancient practice of trading summer internships for assorted favours to its logical conclusion: it has created a market in them.

The charity is called the Second Half Centre, a drop-in centre for older people in London, and it is the brainchild of Jill Shaw Ruddock, a former banker and author of a book that accentuates the positives of life after menopause.

Prospective bidders

The enterprising Ms Ruddock persuaded seven businesses - in finance, fashion, architecture, art and publishing - to offer work placements which she could auction.

The participating companies are Net-a-Porter, ISSA, Oppenheimer, Man Group, Amanda Levete Architect, Peters Fraser & Dunlop and the Gagosian Gallery.

Her note to prospective bidders said:

"You may have already organised work experience for your son or daughter, but you probably have quite a few friends who haven't yet. I would be grateful if you could either PLACE A BID or FORWARD THIS EMAIL on to friends who have children 16 years of age or older...

"Please start the bidding at whatever level you think appropriate... Any internship can be secured immediately with a firm bid of £5,000".

So there you have it: the market price of a short internship for a teenager is £5,000. And after the auction closed, Ms Ruddock had raised around £30,000 (so her representative told me).

Now to state the obvious, many people will be shocked by the idea that money can so directly and crudely secure possible career advantage for the children of the rich.

To be clear, spending a week with Man Group or Oppenheimer is no guarantee of a future massive income in the City. But it provides the intern with valuable knowledge and contacts. And it looks good on a CV.

So the five grand does buy a leg up. And to state the bloomin' obvious, if all internships were sold, then those brought up in social housing or on council estates could say goodbye to any hope of obtaining direct personal experience of work in a top company while young.

The dad who sent me Ms Ruddock's email felt nauseated by the trade.

Honesty and clarity

But I am not sure his reaction is reasonable. He routinely gives a few days desirable work experience in his own respected and high-paying firm to the children of chums.

Money may not be changing hands in his case, but there is still the valuable if intangible trade in favours owed and given.

There is an argument that Ms Ruddock has simply brought some honesty and clarity to this transaction - and made some money for a good cause in the process (she says she has to find imaginative ways to raise money, because only 10% of her funding comes from the public sector).

What she has shown, arguably, is that the process of allocating internships is staggeringly inefficient and unfair, reinforcing the advantages of the haves and further marginalising the have-nots.

Many would say that when a summer work placement can be sold to the rich for £5,000 a go, it shows that the system of allocating desirable placements badly needs cleaning up.