A London law firm has publicly apologised to Harry Potter author J K Rowling for revealing that she has written a detective novel under a pseudonym.
Rowling was revealed as the writer of crime novel The Cuckoo's Calling in The Sunday Times newspaper.
The BBC reports Rowling found out the leak came from Russells, a law firm whom she had assumed she "could expect total confidentiality from".
"I feel very angry that my trust turned out to be misplaced," she said in a statement. "To say that I am disappointed is an understatement.''
Russells Solicitors said on Thursday it apologised "unreservedly". In a statement, it said the information was revealed "during a private conversation".
The Cuckoo's Calling received good reviews when it was first published. It had sold 1500 copies before Rowling was revealed as the author, but the BBC reports it rose more than 5000 places within hours to top Amazon's sales list.
When she was revealed as Galbraith, Rowling issued a statement saying she had "hoped to keep this secret a little longer".