Blakley trained at the Central School of Speech and Drama. In 1998, she won the Ian Charleson Award for her performance in The Seagull at the West Yorkshire Playhouse. She is best-known for her playing Mabel Nesbitt in Robert Altman's Oscar-winning Gosford Park and as Charlotte Lucas in Joe Wright's hugely popular 2005 version of Pride and Prejudice. She will be seen on television screens in the autumn of 2007 in the BBC mini-series Cranford Chronicles in which she features as Martha.
