I loved Widows, particularly because it was a female heist film but it didn’t descend into being a buddy film – the women were flawed and they had their own agency. Was that something that spoke to you?

I love the mess. These women are unapologetic about their circumstances and who they are. There’s this weird thing in film and TV where  a woman has to be perfect and you have to like her and with this [film], it’s not asking you to  like them. You get to see that with men very often but you rarely get to see that with women. And in real life we are not perfect. It’s tiring to think that we have to be.

Does it give you hope that we’re finally moving into a world where women’s experiences are no longer treated as other or singular?

We still have work to do but we are moving into a moment where we can tell stories about women who are multifaceted, who are flawed and different. As women now in the entertainment industries, we don’t want to tell any other kind of story any more, we’re done with that. The more that happens, the more we say no to roles that don’t deserve us, the more we force people to write roles that do. The films that are the most successful are starting to be the stories with women that you just don’t meet very often in films but you do meet in life. Once people get it in their heads that it isn’t something to be afraid of and it actually serves everyone, then we’re laughing.

You said you’ll say no to things – is that easy for you? 

I’m stubborn so I say no to anything I don’t want to do [laughs]. I get scripts that come in and the first thing I look for is if this woman is well-rounded. Especially for a woman of colour, [the roles] can become monolithic: the idea of a woman who yells and shouts too much or the woman who is really, really sexy. [She pauses for a minute and laughingly asks, “Can you hear my dog in the background? He’s trying to get my attention.”] I don’t want to be the person who puts a character on screen who doesn’t show a good example  of what we are as women and  I feel like it is my responsibility to do that. Maybe I’m taking on too much but I feel like that has always been my responsibility.

You’re filming Harriet at the moment, about the American abolitionist and escaped slave Harriet Tubman. Was  she someone you knew much about? 

I made it my business to; she was a woman of colour who’s done incredible things. I’m a geek when it comes to looking up all these stories that don’t get told. And because she was mini like me – she was 5ft1 and extremely strong – and she was doing all of those things by herself, her strength and her will really intrigued me.

Cynthia Erivo on interracial relationships, Viola Davis and flawed women