Keira Knightley said her new film "Misbehaviour", the true story of how the Women's Liberation Movement disrupted the 1970 Miss World competition, felt relevant at a time when people were still fighting for equal treatment.

Knightley, 34, plays a member of the Women's Liberation Movement, which storms the stage of the London theatre where the beauty pageant was being held. That year Miss Grenada won, the first time a black competitor had taken the crown.

The themes of feminism and racism appealed to the actress, she said, as they had ongoing resonance in a world where equality still felt a long way off.

"What I loved about this film was that conversation because it felt so very relevant to what we're still talking about today," Knightley told Reuters in an interview.

Back in 1970, Miss World was the most-watched TV show on the planet with more than 100 million viewers, meaning the protest created quite a stir. Misbehaviour opens in British cinemas on March 13, starring Greg Kinnear as pageant host Bob Hope, the comedian, and Gugu Mbatha-Raw as Miss Grenada.

Knightley is even more conscious of women's rights and related issues like the #MeToo movement which calls out sexual misconduct across the entertainment, politics and business industries, because she is raising two young daughters.

"With social media...I do completely worry about that with my kids and I worry about the kind of images that they're going to be bombarded by," she said.

But Knightly believes progress has been made and the film pays tribute to the women who helped achieve that.

"I think you have to honour and mark the women that created that great progress before us," she said.