Scarlett Johansson: The biggest joy that I have is looking at my daughter

When it comes to squeezing herself into skintight leather for the Avengers movies, Scarlett Johansson is glad to oblige. “I’m always happy to put the catsuit back on,” says the actress, who plays Black Widow in the superhero series.

She’s done it three times already, in two Avengers blockbusters and one Captain America movie, and she’s back in the black leathers for Captain America: Civil War, which is filming now for a spring 2016 release.

She’s the big female star in a testosterone-heavy franchise, but ask her if she minds being called a Marvel Universe sex symbol and 30-year-old Scarlett grins. “Really? Me? Have you seen Chris Hemsworth?”

Hemsworth, of course, is long-haired Thor, strutting his macho stuff alongside the likes of Chris Evans’ Captain America and Robert Downey Jr’s Iron Man.

But the Black Widow is far from a token foxy female, as Scarlett insists: “Black Widow has put in the work and she’s at a place where she’s able to do something for herself.”

The actress, who is married to French journalist Romain Dauriac and mother to 13-month-old Rose, smiles and adds: “Maybe she’s even ready to have a relationship with somebody, but there’s this greater calling that’s pulling her and she very selflessly chooses that. It’s heroic and cool.”

Scarlett is very cool herself. She’s easy-going, comfortable in her own skin and not at all caught up in her own celebrity status. She’s happy to toe the party line, bigging up Avengers: Age Of Ultron, which is out now on Blu-ray and DVD after packing cinemas around the globe and Black Widow’s part in it. But Scarlett can also be funny, declaring that when she gets a new Avengers script: “I just skip through it and go, ‘Black Widow – there she is and there she is again.’ I only read those parts.”

The severe haircut, which is blonde on top and jet-black at the sides, is more rock star than red- carpet fashionista but then Scarlett – who flits between franchise flicks and indies like Under The Skin and Her – plays by her own rules.

She has dabbled in music, with three albums under her belt, but these days her spare time is spent raising her little daughter Rose Dorothy who was born in September 2014. “The biggest joy that I have is looking at Rose,” declares this most glowing of mums.

“When I’m just hanging out with her and we’re doing silly stuff and I make her laugh, the feeling of joy I have is explosive. If I can make her laugh and she gets a big smile on her face, that’s pretty much it. If only you could actually bottle that and carry it around.”

It’s way too soon to know if Rose will follow in her mother’s footsteps but Scarlett started young. She was born in New York to a Danish father, who is an architect, and a mother, who’s a producer and took little Scarlett to auditions.

“For as long as I can remember I wanted to be an actor,” she recalls. “When you’re a kid they send you on a lot of commercial auditions and I was terrible at selling things. I never got those parts. I remember crying in the subway and my mom said, ‘Look, let’s forget it – do something else,’ and I replied. ‘No. You can’t take this away from me. I want to be an actor!’”

“Ever since I was three or four I was very dramatically inclined. I was very outgoing. I loved adults’ attention and I loved to perform. I used to put on shows for my family. My childhood was filled with things that I loved to do and also normal things. I lived in New York and went to a regular school.”

When she wasn’t acting, that is. Scarlett made her big-screen debut at age nine in the 1994 comedy North and one film followed another, then in 2003 Lost In Translation made her a star and a sex symbol. She embraced it, saying: “One of the best things for a woman to hear is that she is sexy.”

But she’s a curvy girl who jokes: “I hope they make a video game of me. At least I wouldn’t have any cellulite then.” But she’s come to terms with her figure. “Everyone in Hollywood is so damn skinny and you constantly feel like you’re not skinny enough. But I have ‘fat days’ and I accept that I’m never going to be rail-thin.”

Then there’s the voice – a deep, distinctive and seductive rasp that is all part of her allure now but may have held her back as a child. “I was always terrible at commercials where I had to speak because my voice was so deep,” she says. “At the age of nine I sounded like a whiskey-drinking, chain-smoking fool.”

In adulthood, the voice hasn’t held her back and she’s enjoying a very varied career. “It would be such a waste to just continue to do the same thing and not take a risk,” she says of her choices. “People were surprised that I wanted to play a comic-book heroine, but I loved Iron Man and

I met with Marvel to see what was possible. I had done my research and the Black Widow character resonated with me. Black Widow is a superhero, but she’s also human. She’s small, but she’s strong. It’s hard not to admire her.”

Scarlett has been married before – to Ryan Reynolds, who she began dating in 2007 and split from in 2011. Dauriac, who reports on the art world and runs a creative advertising agency, sounds like the perfect fit. “It takes a man who’s not only confident in the love that you have for each another but confident in what he has going on in his own career. And we’re interested in each other’s worlds.

He’s interested in my weird, alien entertainment world. It fascinates him because it’s so different to what he knows. And I like to go to art openings with him and talk about art and emerging artists with him.”

She has learned to live with fame but she’s still ambivalent about it. “I don’t think there’s any kind of preparation for sudden celebrity,” says the actress, who was only 19 when Lost In Translation bagged her a Best Actress BAFTA. “I think you almost have this slight nervous breakdown when that kind of media attention happens. You’re doing the same kind of thing that you do all the time only you have to make these weird adjustments. Like you’re buying a slice of pizza and somebody’s outside photographing you, which is weird. It’s very uncomfortable.”

She yearns for the Hollywood of yesteryear, when stars had an air of glamour and mystery about them, and so far she’s managed to resist social media. She’s not on Facebook or Twitter, explaining: “I don’t know how I feel about this idea of ‘now I’m eating dinner and I want everyone to know’ or ‘I just mailed a letter and dropped off my kids’. That to me is a very strange phenomenon. I can’t think of anything I’d rather do less than have to continuously share details of my everyday life.”

That explains why she’s cautious about saying too much about motherhood, insisting that she’s no expert. “I don’t profess to know anything more about parenting than anybody else,” she says. “I think you just have to encourage your kids to be who they are and not live in the shadow of your accomplishments.

“Before Rose I just made the choices that were affecting me, but now I’m responsible for somebody else. I think having any kind of huge life-changing event happen to you – such as having children – is very, very inspiring. I think it will enrich my work as well as my understanding of myself.”