She is best known for her portrayal of Katherine in the film Under The Tuscan Sun. Weeks after her appearance in Doctor Who, she played Alice's mother in the billion-dollar-grossing Alice in Wonderland. In 2014, she portrayed Lady Smallwood in the Sherlock episode His Last Vow, written by Steven Moffat, directed by Nick Hurran, produced by Sue Vertue and executive produced by Moffat, Mark Gatiss and Beryl Vertue.
She also contributed to the charity reference book Behind the Sofa: Celebrity Memories of Doctor Who.
At the time of filming The Waters of Mars, Duncan was fifty-eight years old. As her character was identified by the BBC as the Doctor's companion, this made her the oldest actor to play a companion in the franchise's history. This distinction lasted a little over a month until her record was well surpassed by eighty-year-old Bernard Cribbins in The End of Time.
- Internet Movie Database at the