The argument for doing this is that there are excessive costs associated with running the playground and, subsequently, it is unfair for Wandsworth taxpayers to subsidise taxpayers from other parts of London who use the playground.
There are many, many problems with this, not least the effect it could have on children from poor families; children which most of us presumably believe should have as equal a chance as any to play.
Besides this however, there also seems to be something deeply, morally offensive about the idea. It is instantly reminiscent of the Coalition's proposals to privatise forestry. Just as that idea offended the nation, I can see this one doing exactly the same. Introducing a market mechanism into a playground devalues and corrupts what playgrounds are for: a collective, universal enjoyment for each and every child.
Public unease at the use of the market - whether in a forest, a prison or a playground - reminds me of an argument made by the philosopher Michael Sandel: There are some things money can't buy, and there are some things money shouldn't buy.
If we do let money buy precious, valued goods like playgrounds, we risk forgetting why we built them in the first place.