These days, banker-bashing is a popular sport for politicians of all stripes. For not only are the banks being blamed for unleashing financial disaster – while paying the bankers fat bonuses – they are also being blamed for slashing loans in a way that is now triggering a recession.

But is that perception really right? If you take a look at some recent research produced by Citigroup, it might seem not. For if Citi data are correct, the real source of the current credit crunch is not a collapse in bank loans, but the implosion of the shadow banking world.