Now compare Draghi's attitude to the job of a central bank with that of Mervyn King, the governor of the Bank of England. The global inter-bank market seized up in early August 2007. As many banks had used that market as their main source of funds in previous years, they suddenly faced a severe problem. Could they in coming months and quarters find enough cash to finance their assets? On August 9, 2007, leading British banks approached the Bank of England for an easing of collateral requirements on so-called "repurchase operations". They expected the Bank to be flexible and pragmatic, as it had been in the past; they thought that their central bank would respond to their cash predicament in much the same way as Draghi has in his recent dealings with their European counterparts. 

But Mervyn King and Mario Draghi have utterly different views. King gave Britain's banks a dusty answer. No, the collateral requirements could not be eased and the Bank of England would provide no special cash help. The money markets quickly realised that without central bank help several British institutions were at risk. The Northern Rock crisis — which saw the first run on a British bank for over a century — started about a month after the acrimonious August 9 stand-off. 

Still Britain's banks hoped that a long-term loan facility would be extended to them by the Bank of England. One revelation of Alistair Darling's memoir Back from the Brink is that he had a private meeting with the CEO of the Royal Bank of Scotland Fred Goodwin in Edinburgh in Christmas 2007. Goodwin argued that the banks' key problem was a lack of liquidity, which could be countered by a long-term central bank loan. Apparently the conversation was cordial and relaxed, but in the ensuing months Darling got nowhere with King. In evidence to the Treasury Committee of the House of Commons in September 2008, King insisted that it was not a central bank's responsibility to extend long-term finance to anyone. That — in his view — was a job for either the government or the private sector. 

Intellectually, Draghi and King are at opposite ends of a spectrum of views on what a modern central bank should do. But a vital practical question arises from their debate. What would have happened to Britain's banks and its economy over the next four years if Mario Draghi (or a Mario Draghi clone), rather than Mervyn King, had been governor of the Bank of England in August 2007?