It would be distracting if I took my shirt off and had an eight-pack

‘Scarlett is pregnant!’ scream the world’s headlines but The Avengers star is refusing to confirm it. Do stories like that make her feel extra protective of her private life? ‘My private parts?’ she exclaims, teasingly pretending to mishear.

‘The trappings of this job mean I always feel like I’m protecting not just my personal life but my family, my partner [pretty French fiancé Romain Dauriac], my lifestyle, my address, everything.

‘Several years ago I had that whole awful hacking incident’ – when nude selfies she had once sent to ex-husband Ryan Reynolds were intercepted and posted online – ‘which made me feel so paranoid. But I am trying not to let it affect me.’

‘Sexually overwhelming,’ according to her frequent director Woody Allen (Vicky Cristina Barcelona, Scoop, Match Point), Johansson was twice voted sexiest woman alive by Esquire magazine (2006 and 2013), so you’d think her latest role, as a sexy, man-eating alien in Under The Skin, would be a doddle. Instead, this dark masterpiece compelled the Hollywood starlet to explore a whole new edgy, unknown territory: Glasgow.

‘Thrilling’, ‘terrifying’ and ‘delicious’ are how she juicily describes the experience of driving round Scottish streets, disguised only by a dark wig, attempting to pick up real-life male strangers and take them back to her house, apparently for sex, while director Jonathan Glazer (Sexy Beast) and crew hid in the back of the van, secretly filming. She was never attacked. She was never recognised.

‘If people aren’t expecting you to be there, then you’re somehow not part of their reality,’ she explains, the sheer oddity of Scarlett Johansson being in a Glasgow lay-by rendering her invisible. And does her mega-fame ever make her feel like an alien in the ‘normal’ world? ‘I see some of the young actors and young celebrities today desperately trying to fit back into society,’ she says with the sage air of a showbiz veteran, ‘which I totally understand. But really, once you accept your fate as someone who’s a recognisable person, who’s no longer anonymous, I think you have a much easier time fitting in than if you are constantly trying to be “normal”.’

Aged 29, Johansson is still technically a ‘young actor’ herself. Indeed, with 40 films including Girl With A Pearl Earring and recent Oscar winner Her to her credit, not to mention two studio albums as a singer, I tell her it’s hard to believe how young she still is ‘…because I look so old!’ she finishes, laughing uproariously.

She was just ten when she made her film debut (North), 14 when The Horse Whisperer came out and only 17 when she gave her Bafta-winning turn in Lost In Translation – it’s no wonder it feels like this four-time Golden Globe nominee has been around forever.

‘In a lot of ways I am exactly the same as I was when I was 12,’ the Danish-Jewish actress confesses – which marks the point where her BC (Before Celebrity) era would have ended. ‘I try to live as normal a life as I can. I live in New York and that allows for me to have everyday encounters with people in life that I might not have if I lived in a big LA mansion on a hill. Of course, that doesn’t mean I am ever going to be thrilled to be in a women’s locker room – but who is, right?’

She gives an intimate, deep, warm, throaty chuckle that instantly makes me feel like I’m chatting to one of my oldest gal pals, rather than ScarJo, international sex bomb.

Under The Skin may require Johansson to strip down to her undies but her curvaceous body is, bravely for an A-lister, not toned to hard-body perfection. ‘Of course, like any woman, I was thinking: “Oh God, there are going to be a million screen shots of this.” But it would be kind of distracting if I took off my shirt and I had, like, an eight-pack – not that I would ever have one! The character should look available and womanly – a little bit exotic, yes, but like she could fit in. It’s not like she’s some superhero, you know?’

Speaking of which, superhero fans have been getting their tights in a twist over whether the pregnancy-of-which-I-shall-not-speak will mean Johansson’s Black Widow character is downsized in the about-to-shoot The Avengers 2. She won’t be drawn on that, except to say it would still probably take her only three weeks’ training to be catsuit-ready, with the raw vegan diet that entails, if she can only stay off the Sour Patch Kids sweeties. ‘That is something I can never turn down, no matter how much kale I’m eating,’ she says.

And she’s a mean baker too. ‘I don’t believe in the whole raw egg thing,’ she declares. ‘Licking the spoon is the best part. Sometimes the mix will barely make it to the oven.
‘My signature baked good is a vegan banana chocolate chip muffin – I can modestly say I have had marriage proposals from those.’ How about Scotland’s infamous deep-fried Mars Bars – did she develop a craving for them? ‘You know, I didn’t find one,’ she says, ‘but I did try Irn-Bru.’ She pauses, mentally re-visiting its unique orangeness. ‘I just don’t think I’m Scottish enough for Irn-Bru,’ she concludes gravely.