Kelly became interested in drama whilst at school in London's Tolworth Girls' School. Her first role was in Lynda La Plante's Prime Suspect, alongside Helen Mirren, when she was aged 18.
She's since gone on to star in a range of shows including The Graduate, Above Suspicion and films including Sherlock Holmes and Me and Orson Welles.
For her TV work she's arguably best known for her crime dramas, which is fitting as her father was in the police force.
Awards: She was the youngest person ever nominated for the Laurence Olivier Theatre Award, aged 26, in 2003. She did not win, however. In 2005 she won the Best Newcomer Award at the 2005 Cannes Film Festival for her role as Wendy in The Russian Dolls.