Juliet Stevenson thought she would be dismissed as "too posh" for her latest role.
The Bend It Like Beckham and Truly, Madly, Deeply actress plays a grieving mother who takes justice into her own hands in Jimmy McGovern's new hard-hitting TV series, Accused.
Juliet, 54, admitted she didn't expect to get the part, saying: "I was thrilled to get it because I thought, 'He probably won't want to work with me, he'll think I'm a posh person from down south, he'll want someone else to play this gritty role', so I was really chuffed to get it."
The London actress plays a primary school teacher, Helen, whose 18-year-old son dies on his first day at a new job in a factory in the drama, from the writer of Cracker and The Street.
Helen discovers her fighting spirit when she feels factory bosses are not being entirely honest about the circumstances of his death.
Juliet said: "She's a relatively mature, thinking woman but her life hasn't led her to question authority or ever ask questions of the law.
"The guts and the heart are wrenched out of her life, and in her grief she starts to wonder how it happened.
"When she's told it was her son's fault and he's being smeared, she takes them on, then the Crown, then the police and then the law, as each of them fails her," Juliet said.
The actress can next be seen on screen alongside Romola Garai, Ben Wishaw and Dominic West in The Hour, a BBC drama set in the Fifties.
:: Accused: Helen's Story is on BBC One on Monday, November 29.