Mervyn King and George Osborne are the odd couple of British politics: a self-consciously cerebral governor of the Bank of England and an intensely political Tory shadow chancellor united in condemnation of the government’s handling of the financial crisis. For now, the relationship works to mutual advantage. It may not always be so.

The other day Mr King launched a public onslaught on the Treasury’s plans for supervision of the financial system. In a nutshell, his argument was that the banks had been let off scot-free. The only way to prevent a repeat of the crash of 2008 was to separate the utility functions of deposit-taking and lending from “casino” investment banking.