As a young loan collector in rural Minnesota, John Stumpf, chief executive of Wells Fargo, was once dispatched to repossess a chainsaw from a defaulting customer.

When he arrived at the house to pick up the tool, he found its owner less than welcoming. “He looked up at me, dropped the chainsaw, picked up a rifle, and said: ‘Why don’t you come and get it?’,” Mr Stumpf recalls in his office in Wells’ headquarters in downtown San Francisco. “I replied: ‘I don’t think we need that saw right now. See you later’.”