Nicola Jane Walker (born 15 May 1970) is an English actress, known for her starring roles in various British television programmes from the 1990s onwards, including that of Ruth Evershed in the spy drama Spooks (2003–2006 and 2009–2011), DCI Cassie Stuart in Unforgotten (2015–2021) and Hannah Stern in The Split (2018–2024). She has also worked...