Yesterday it emerged that US and UK regulators have fined five banks a total of two billion pounds for manipulating exchange rates.

Channel 4's economics editor Paul Mason found himself standing outside Royal Bank of Scotland's headquarters in London, reporting on yet another financial scandal, and let loose about his frustration.

"After six years why do we have to keep coming?

"If the banks had the same scrutiny over the traders and their own managers as they haver over the camera crews standing outside it, where you get a security guard coming and asking what you're doing, we might not be in this situation."

Mason finds it hard to believe that despite the seemingly inevitable recurrence of banking misconduct, financial regulators have still not put the boot down.

"All we can ask is that the regulators do their job pro actively, that they actually get on the case... and stop wrongdoing in advance. What's so hard about it?"