As I've mentioned already today, this is a week of pretty intense campaigning for a Robin Hood Tax - a tax on financial transactions.

I wrote about this quite a bit in a report I did in 2009 called Taxing Banks. The data will be a little different now but the principle remains the same - which is that banks are undertaxed, financial speculation is to a very large degree in itself a zero-sum game that is, however, socially harmful because of the resources it draws away from productive use and if more tax was applied to it the volume of transactions might fall, those socially useless resources might be reallocated to productive use and we'd all be better off.

For these who want the somewhat longer version, Taxing Banks is here.