What does the Brooks Coulson phone-hacking verdict tell us about editors’ responsibility for their newsrooms?

The verdict in the phone-hacking trial raises an interesting question: how much do editors know about what happens in their newsrooms? I think the problem at the News of the World was symptomatic of a certain period in tabloid journalism. The problem in that newsroom was particular to the people involved and perhaps the proprietor, too. But even allowing for the exceptionalism of this case, there is a wider issue about journalistic leadership