The "biggest problem" in the international financial system – ending ‘too big to fail' – can only be solved using a combination of 'bail-in', effective planning and cross-border co-operation, according to Paul Tucker, deputy governor for financial stability at the Bank of England (BoE).

Tucker has long been a proponent of bail-in as the method of making a bank's creditors bear the cost of a bank's failure. Under such a system, the various layers of the creditor hierarchy are written down until