Keira Knightley wasn't 'allowed' to attempt local accent for Boston Strangler film

Keira Knightley wasn't "allowed" to attempt a Boston accent for the Boston Strangler film.

In the upcoming historical crime drama, the British actress portrays reporter Loretta McLaughlin, who broke the story about the killer in the 1960s.

While Keira was keen to try out a local accent for the part, during an appearance on The Tonight Show Starring Jimmy Fallon on Wednesday, she admitted director Matt Ruskin shut down the idea.

"Well, I wanted to do the Boston accent," Keira began, before noting how Matt was very protective of the people of his hometown. "I mean, if you weren't from the street that the character was from in Boston, you were not allowed to do the Boston accent."

In the end, Pride & Prejudice star agreed to do a "standard" American accent.

"Every single actor went in going, 'Boston accent! It's our time,'" the 37-year-old recalled. "(But), yeah, no, we were not allowed. So, it's a standard American accent. There's no Boston."

Elsewhere in the conversation, Keira discussed how Loretta and her fellow journalist, Jean Cole (Carrie Coon), challenged the sexism of the era.

"I thought, 'Wow, this is such a complicated story. And so interesting.' And what I didn't realise, was that there are these two female journalists right at the centre of the story... they were the two that really, kind of, went after it. They first linked the killings, they even named the killer, the Boston Strangler. And yet, when you Google it, their part of that history has largely been erased," she continued. "It felt cool to see it through that female gaze, and to put these two journalists, sort of, in the centre of it."

Boston Strangler, also starring Chris Cooper and Alessandro Nivola, is set to debut on Hulu and Disney+ on Friday.