Offered a place at the
Royal Academy of Dramatic Art on graduation from Cambridge, Walker already had some roles and an agent, so she decided to pursue her acting career. Based in London, she shared a flat with Perkins,
Sarah Phelps, and
Emma Kennedy. She acted at the
Edinburgh Festival and the
London Festival Fringe. She has also appeared in guest roles in episodes of series such as
Dalziel and Pascoe,
Jonathan Creek,
Pie in the Sky, and
Broken News. She played the leading part of DI Susan Taylor in the
ITV thriller serial
Touching Evil in 1997, co-starring opposite
Robson Green. She also appeared in its two sequel serials in 1998 and 1999. Also in 1999, she took the lead role in the
post-apocalyptic drama serial
The Last Train, also screened on ITV (and written by future
Spooks writer
Matthew Graham). Also in 2003, Walker played
Molly Millions in the BBC Radio adaptation of
Neuromancer by
William Gibson. In 2003, with the production team of
Kudos Television looking to replace the character played by
Jenny Agutter in Series 1 of
Spooks, the part of
Ruth Evershed was specially written for Walker from Series 2. In 2007, Walker had a prominent supporting role as a child snatcher in the ITV1 drama serial
Torn and appeared in the BBC adaptation of
Oliver Twist. In 2009, she appeared as a maid in
a new BBC adaptation of
Henry James'
The Turn of the Screw, which also starred
Michelle Dockery and
Sue Johnston. In 2010, Walker appeared as a beleaguered wife (Linda Shand) of a murderer in an episode of the BBC One crime thriller
Luther. In February 2011, she appeared as nervous social worker Wendy in the BBC TV series
Being Human. In February 2012, she played a major character in the one off BBC crime drama
Inside Men. From 2012 to 2020, she appeared as Gillian Greenwood (née Buttershaw) alongside
Derek Jacobi,
Anne Reid and
Sarah Lancashire in five series of the
BBC original drama
Last Tango in Halifax. Walker was twice nominated (2014, 2017) for a Television BAFTA for Best Supporting Actress for this role. In February and March 2013, Walker reunited with her former
Cambridge Footlights colleague
Sue Perkins in the BBC comedy
Heading Out. She then appeared in the second series of ''
Prisoners' Wives and the third series of Scott & Bailey'' playing Helen Bartlett. In 2015, she appeared as Jackie "Stevie" Stevenson, the colleague of DI John River played by
Stellan Skarsgård, in the BBC drama series
River. Walker starred, alongside actor
Sanjeev Bhaskar, in series one through four (2015–2021) of the ITV drama series
Unforgotten as DCI Cassie Stuart. From 2018 to 2022, Walker starred as Hannah Defoe Stern, a divorce lawyer, in all three series of the BBC drama series
The Split. Also in 2018, she played Reverend Jane Oliver in the BBC2 serial
Collateral. Walker was number 10 on the
Radio Times TV 100 list for 2018, a list said to be determined by television executives and broadcasting veterans. In 2021, she starred in the British
crime drama television series
Annika, based on the
BBC Radio 4 drama Annika Stranded, with Walker reprising the title role. Produced by
Black Camel Pictures for
Alibi and
All3Media, the first episode aired on 17 August 2021. This is the eighth different police officer or detective role she has played on British TV. In August 2022, it was announced that a second series of
Annika had been commissioned. On 20 May 2023, the first series of
Annika began airing on
BBC One. In 2022, Walker appeared in
Stefan Golaszewski's drama,
Marriage alongside
Sean Bean. The series received mixed reviews from both critics and viewers. In 2024, Walker appeared in the Sky Atlantic TV series
Mary & George as
Lady Elizabeth Hatton.
Theatre Walker won an
Olivier Award in 2013 for Best Supporting Actress in her role as Judy, the main character Christopher's mother, in
The Curious Incident of the Dog in the Night-Time. The play won seven Olivier Awards, equalling ''
Matilda the Musical's'' record win in 2012. In 2014, she starred alongside
Mark Strong and
Phoebe Fox in
Arthur Miller's play
A View from the Bridge, at the
Young Vic theatre. The play received extremely positive reviews from critics and transferred to
Wyndham's Theatre in London's
West End in 2015 and to the
Lyceum Theatre on
Broadway. In 2022 she starred as Miss Lily Moffat in the
National Theatre revival in London of
The Corn is Green, the 1938 autobiographical play by
Emlyn Williams.
Film In film, Walker's roles have tended to be smaller supporting parts. Her most prominent role was as one half of the folk duo in
Four Weddings and a Funeral (1994), who sing "
Can't Smile Without You" during the first church service and "
Stand By Your Man" at the reception. She also appeared in the feature film adaptation of the television series
Thunderbirds (2004). In 2005, she portrayed a British journalist caught up in the
Rwandan genocide in
Shooting Dogs.
Audio In 2002, Walker co-starred in the BBC radio production of
William Gibson's cyberpunk novel
Neuromancer. In July 2011, she played the significant supporting role of Medtech
Liv Chenka in the
Big Finish Productions Doctor Who audio drama
Robophobia, opposite
Sylvester McCoy as the
Seventh Doctor. The Chenka character proved popular both with producers and listeners, and in February 2014 Walker returned to the role, this time as a foil for
Paul McGann's
Eighth Doctor in
Dark Eyes 2. The character was sustained throughout
Dark Eyes 3 and
Dark Eyes 4, at the end of which it was revealed that Chenka was to continue as the Doctor's established travelling companion. Walker returned to the role in the follow-up four-volume
Doom Coalition,
Ravenous and
Stranded. Walker reprised the role of Chenka in 2022 in
The Eighth Doctor Adventures: What Lies Inside? and
The Eighth Doctor Adventures: Connections. She also played the role in an 18-part series titled
The Robots, starring alongside
Claire Rushbrook. In 2017, she starred in the company's adaptation of the
H. G. Wells novel
The Shape of Things to Come. Since 2013, Walker has voiced the Norwegian detective Annika Strandhed in the BBC Radio 4 drama series
Annika Stranded by Nick Walker. From 2018 to 2023 she played the role of Dr. Eleanor Peck in the BBC Radio 4 production
The Lovecraft Investigations alongside her husband
Barnaby Kay. ==Personal life==