The actress also corralled director Niki Caro and the cast and crew for a group shot on the set in Prague, Czech Republic, and reveals she loves working with women in power because they "make room for other women".

The fervent feminist, who has applauded peers with pro-women messages this year (15), says, "I've never been on a set with so many women. We're not even 50 per cent of the crew... but it's way more than I've ever worked with on a film before.

"There are female producers (Diane Levin, Kim Zubick and Katie MCNeill), a female screenwriter (Angela Workman), a female novelist (Diane Ackerman), a female protagonist and a female director. I've never seen a female camera operator like Rachael Levine on one of my films. And I've never, ever seen a female stunt co-ordinator like Antje 'Angie' Rau.

"Usually, on a movie, it would be me and maybe two or three other women, even though there are 100 people there. It's crazy."

Based on Ackerman's book about Antonina Zabinska, who sheltered people in animal cages at the Warsaw Zoo during the Nazi invasion of Poland at the beginning of World War Two, Chastain insists The Zookeeper's Wife will turn heads, because it will prove what a female director is capable of.

"Some people might say a woman can't direct this because of that, or a man can't direct that because of this," she explains. "I don't like to do that. Look at Kathryn Bigelow - she can do incredible action films. Or Anthony Minghella, who directed the most beautiful, sensitive romances. For me, sex really isn't the qualifier in the way someone directs.

"And the wonderful thing about having so many women on set is there hasn't been anyone who has screamed or anything like that. It's a very collaborative experience, and it's been heaven for me. We all hang out all the time; there are no strange power plays or egos. We know how rare making this kind of film is. We're giddy with happiness."