That’s RK Galbraith to you.
The Guardian reported today that a lawyer, or solicitor in British terms, was responsible for the leaking of JK Rowling’s secret pseudonym (Robert Galbraith). The lawyer let his wife’s best friend in on the secret, a secret exceedingly few people knew. That friend in turn was the person who first tweeted Rowling’s secret. The lawyer and firm contacted Rowling’s agent as soon as they realized the pseudonym had been unmasked and apologized.
In the United States, lawyers have a very strong duty of confidentiality that covers any information that relates to the representation, and I assume that British solicitors have a very similar duty. In fact, the tradition of confidentiality is so strong that it is a very significant part of most attorney’s self-image.
In the US, such a revelation could expose the offending lawyer to both professional discipline (up to losing their license to practice law) and malpractice liability. The breach of the ethical duty creates a slam dunk case for the breach of care that triggers civil liability in a legal malpractice case. So, in this particular case, proving liability would not be difficult. What would be difficult would be proving damages, after all Rowling’s sales actually increased after the breach of confidence. So, if this had happened in the US, she might win a malpractice case against the attorney but be awarded nominal damages (e.g. $1).
I teach professional responsibility and ethics to baby lawyers (i.e. law students). I try to stress to them that damaging breaches in confidentiality are often the confluence of seemingly innocuous conversations and bad luck; rarely is it dastardly conduct.
Writer-in-Law 
An interesting thing our professional responsibility prof said was “if it feels irresistible to share a piece of information, never believe that the person you tell it to – who lacks your professional obligations to keep it secret – will resist that temptation.” He also said that the thing that gets you disbarred is pretty much always a favor done for a friend.
I’m going to have to steal that quote for my class this fall!