“This is probably another lesson to us all but you can put all sorts of machinery in place, and e-mail is still a difficult thing to control. It is also difficult to control someone with a grudge,” Norton Rose partner David Ashworth says.

Ashworth is referring to the press reaction to an e-mailed hoax sent by a Herbert Smith trainee. And Norton Rose is in a good position to know, having faced similar headlines in December after the mildly explicit e-mails of Bradley Chait reached 10 million people globally.