Back in early 2007, during the height of the credit bubble, one of WallStreet's most senior bankers criticised me over some of my articles about the complex credit world. “Why do you keep writing that structured finance is murky and opaque?” he railed. “It's not opaque - anyone can get anything they want off a Bloomberg machine!”

“But what about that 99 per cent of the population that is not on Bloomberg?” I asked, pointing out that most politicians and journalists - let alone ordinary voters - did not have access to those hallowed Bloomberg terminals, which allow financiers to access data and place trades, as well as providing news coverage. How could they get information? That question elicited a long, pregnant pause. This particular banker clearly assumed that everyone who mattered had a Bloomberg terminal. He did not know how to reply.

This little exchange has popped into my head repeatedly in recent days, as allegations have emerged that some Bloomberg journalists in recent years have been looking at details of clients' terminals. As the revelations have tumbled out, this has infuriated some financiers. Meanwhile, Bloomberg executives have rushed to reassure their clients that they respect confidentiality - and are now tightening internal controls to separate the journalism from the commercial terminal business.