The large literature on macro prudential regulation stresses the importance of using information obtained in the supervisory process to check for emerging bubbles and other imbalances.

FORBES: Euro Area Banking Union: Should Bank Supervision and Monetary Policy Be Separated?

The development of supervisory guidances is a process which often involves soliciting comments from the industry and the public and, where applicable, developing a consensus among the banking regulators.

FORBES: Transcript

"Barclays has fully collaborated with the supervisory authorities and has been completely transparent throughout the process, " a spokesman for the bank said, adding that it had put measures in place to make sure such an incident would never happen again.

MSN: Barclays Spanish unit fined for mis-rating bonds

But there is an element of that, according to those close to the appointment process - which is being carried out by Deutsche's supervisory board with Ackermann (I am reliably told) in an advisory role (which would not be seen as best practice in the UK).

BBC: How Deutsch do you have to be to run Deutsche Bank?