In film and television, her credits include Carry On Cleo (1964), The Wildcats of St Trinian's (1980), Buster (1988), Three Men and a Little Lady (1990), The Boy in the Striped Pyjamas (2008) and Edie (2017).

[7] After wartime evacuation to Wallingford, Oxfordshire (at that time in Berkshire) and to Crewkerne, Somerset, Hancock attended Dartford County Grammar School.

[9] Hancock worked in repertory during the 1950s and made her West End debut in 1958, replacing Joan Sims in the play Breath of Spring.

In 1978, she played Miss Hannigan in the original London cast of the musical Annie at the Victoria Palace Theatre and two years later, she played Mrs Lovett in the original London production of the musical Sweeney Todd at the Theatre Royal, Drury Lane; her portrayal was described as having "caught the love-story element perfectly.

[14] In 2006, Hancock played the role of Fräulein Schneider in the West End revival of the musical Cabaret at the Lyric Theatre.

In 2009, she spent over a year playing Mother Superior in Sister Act the Musical at the London Palladium for which she was nominated for an Olivier Award.

Her other television credits include Doctor Who (playing a parody of Margaret Thatcher in The Happiness Patrol),[21] Kavanagh QC (opposite her husband, John Thaw), Gone to the Dogs, Brighton Belles, EastEnders, The Russian Bride, Bedtime, Fortysomething, Feather Boy, Bleak House, New Tricks, Hustle and The Catherine Tate Show.

In 2008, she played the part of a terminally ill patient who travelled to Switzerland for an assisted suicide in one of The Last Word monologues for the BBC, in a role that was written especially for her by Hugo Blick.

From December 2016 until its conclusion in January 2019, she starred alongside Dawn French, Emilia Fox and Iain Glen in all three seasons of the Sky One comedy drama series Delicious.

[citation needed] In January 2017, Hancock made a guest appearance in an episode of the Inspector Morse prequel Endeavour alongside her stepdaughter Abigail Thaw.

[28] In 2021, she appeared in more Great Canal Journeys as well as the Sky One fantasy drama A Discovery of Witches as Goody Alsop, and as Eileen in ITV's Unforgotten.

In 1995 Hancock provided the voice of Granny Weatherwax in BBC Radio 4's adaptation of Terry Pratchett's Discworld novel Wyrd Sisters.

From March to May 2010, she appeared as a judge on the BBC show Over the Rainbow, along with Charlotte Church, Andrew Lloyd Webber and John Partridge.

[32] Hancock was the subject of This Is Your Life in 1977 when she was surprised by Eamonn Andrews at the curtain call of the play The Bed Before Yesterday at the Lyric Theatre, London.