Where to begin with Wallis Day? That’s not a rhetorical question but a genuine problem, one that will surely vex many writers in years to come. In prose, as in life, getting started tends to be the difficult bit. The fortunate journalist departs an interview with the opening sentence already in mind. Often it takes until transcription to dig out a quote that will arrest the reader, and yield the door onto the article and its subject. Sometimes you slouch there, chin in hands, trying to spot a glint of semi-inspiration amid the thicket of words on screen.

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An interview with Wallis Day is a little different. There are so many ways to unspool her story, so many tantalizing threads, it’s impossible to know which to choose.

For example: Wallis Day is a genius. That’s not hyperbole, nor does it mean she’s a genius in the manner of, say, Lionel Messi at football or Hendrix on the guitar (ie. niche). Her IQ of 143 is comfortably in the top 1% of the UK population, and would qualify her for Mensa on the Stanford-Binet test. She entered education a year early, and moved through 11 schools in 12 years before finally dropping out at sixth form – acting, not academia, her chosen path. Which was a shame for her dad, who’d harboured legitimate hopes that Wallis might one day become an astronaut.

Here’s another: Wallis Day wants to be James Bond. She’s trained in MMA, boxing and Muay Thai; speaks passable Russian; and although she doesn’t own a motorbike she most certainly can handle one. “I ride when I’m in LA sometimes – people are always surprised when I take the helmet off.” Formerly a competitive swimmer, Day trained to represent Great Britain in the 2012 Olympics. She performs her own stunts, naturally. And then there’s the (not-so) small matter of her IQ.

One more: we all have to start somewhere. Wallis Day started in Budapest, playing the lead role in a Nintendo DS commercial. The only role, in fact; she bounced around a sofa, all blonde bonhomie, playing Mario Land, or rather reacting to playing Mario Land: “Ding, ding, ding – jackpot!” as more gold coins are added to the swag. She earned real money for that gig, not much but a damn sight better than the £4.30 hourly rate for her job at a London retail store; enough to feel she had made the right decision, and believe the coming years might yield more than Mario and Luigi.

Later, after the shoot wrapped, someone put on Coldplay’s ‘Paradise’ – “when she was just a girl, she expected the world” – and Day stood on the balcony outside and felt validated as an actress for the first time in her life. “Every time I hear that song it reminds me of that feeling of finishing my first job and being over the moon.”

She shares this story at the Booking Office at King’s Cross (the restaurant, not, you know…). Day is all enthusiasm: for acting, which she palpably adores, but also life and the adventures that come with it. An hour spent in her company passes quickly, but then she’s never been one for hanging around.

The whole academic route stopped working for me: I felt like my creative side was suffering, and I felt like I was being starved of that creativity

The week of our interview, Day flies to the South by Southwest festival in Texas for the premiere of Krypton, a Superman prequel set 200 years before the arrival (and immediate departure) of Kal-El and his bright red pants. The series promises a bold reimagining of mythologies; showrunner Cameron Welsh has told fans, “What you thought you knew about Krypton, you can forget.”

Day is the Machiavellian Nyssa-Vex, a junior magistrate and “a bit of a villain. She’s naughty, she’s fun, she’s intelligent, and she’s very mysterious. Totally enigmatic.”

When an actor talks about ‘connecting’ with their character, it’s often more spiel than sentiment: “I asked myself, what’s the motivation of Krool the Alien King? Ultimately, he’s a survivor...” Yet Day knew she had to play Nyssa-Vex. She sort out the casting manager and asked to audition – and was refused.

Undaunted, Day sent over a self-tape. It was good enough to score her an audition, then several more. Then, finally, a screen test. “It was me and three or four Asian girls, and I was like, ‘why did I push this? They obviously don’t like blonde girls.’”

Faced with her big moment, Day blew it – or so she assumed. “I thought it went awful, came out crying”. A week later, her 22nd birthday, the tears were back. She’d won the role. “I cried my eyes out. My entire birthday.”

A firm believer that “everyone is born good”, Day nonetheless has an affinity for the dark side – searching for chinks of light amid otherwise murky souls. “Villains are bad for a reason. I don’t think they’re born bad; I think they’ve been through something.”

Her devotion to Nyssa is tangible. “She’s a badass! I love playing bad characters. I feel like it’s a challenge because you have to make the audience almost love someone before they hate them. For an audience to hate a character they have to care about the character, a little bit, whether they like to admit it or not.”

The pair sound a perfect match: “She’s very highly skilled and highly equipped. At the start people just see her as a junior magistrate, and are surprised to learn that she’s up to quite a high standard of intelligence and combat.” Words applicable not only to Nyssa-Vex but also, say, a young woman with an IQ of 143 and a penchant for mixed martial arts.

Acting is more than a vocation for Day, it’s a release, perhaps even a form of salvation. As a child the combination of high intellect, low boredom threshold and an infinite capacity for mischief resulted in Day being ejected from schools almost as quickly as she was enrolled.

“I had a massive problem at school: the whole system just never worked for me.”

After starting school aged two and a half – “my mind was so active. I just read and read” – Day went through 11 before her 16th birthday.

Eleven?

“Yeah. I just kept getting kicked out.”

What for?

“Honestly, just bad behaviour.”

She doesn’t disclose details – “I’ll say the word ‘fire’. Won’t tell the story” – but as she talks a picture emerges, not of a tearaway delinquent but an intelligent, creative mind stifled by a system that encourages intelligence and creativity, yet largely on its own terms.

“I never tried to excel academically, which resulted in me getting bored in classrooms. And because I was moving school, I was moving between different years, and in different years, different schools were taught different curricular. So I’d already learnt what I was now learning, and for a child who was already further ahead... I became bored, and that’s when I started to misbehave.

“The whole academic route stopped working for me: I felt like my creative side was suffering, and I felt like I was being starved of that creativity. As a creative person, it’s more of a hunger and a need than a desire and a want. I felt a huge part of me was missing.”

My parents knew I wasn’t going to come to London and party; I was genuinely going to try and give acting my all

Joining a modelling agency aged 13 didn’t exactly help with her academic focus. Day had hoped modelling might provide a route into acting. “I just Googled ‘modelling agency London’ and Models 1 was the first one to come up. I took down some photos from my bedroom and circled my face and sent them off in a letter to Models 1.

“My parents got a call the next day – ‘This is Models 1’ – and my Dad thought it was an aeroplane models company.”

Once realisation dawned – oh, that type of runway – parental support was absolute. Her mother chaperoned Wallis to all her shoots, and even made cups of tea for the crew.

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Inevitably, the dual lifestyles – schoolgirl by day, model, well, also by day – began to clash. “I was doing my GCSEs a year early, and ended up skiving a lot to go and do shoots, which I didn’t tell my Mum about. Then I would stay in London and end up going to some Vogue party or whatever. At 14!

“My parents weren’t over the moon about that side of stuff, but fuck it, you have to do it, and I’m glad that I did it then rather than doing it all now for the first time. I think I’ve saved myself a lot time.”

Opting out of sixth form to pursue an acting career was a major decision, but also the only legitimate route to happiness. “My parents were terrified but just wanted me to be happy. They knew I wasn’t going to come to London and party; I was genuinely going to try and give it my all.”

Aged 16, Day moved into a tiny student flat in Tottenham, the spare room of a colleague at her new job at the retail store. “It wasn’t even a room, it was a cupboard. My single bed didn’t fit, the mattress was curved up against the wall. Instead of a bedside table I had a pile of clothes and a lamp, and the door would hit the mattress every time it opened.”

Yet she was happy, pursuing her dream and living life on her own terms. An agent was found; auditions attended on lunchtime breaks. Progress accelerated. After the Budapest commercial came a brief stint on Hollyoaks: Day played Holly Cunningham from 2012-13 before quitting the show to study drama at Arts Educational, land further TV roles on Jekyll & Hyde and The Royals. Then, Krypton – and our Wallis Day biography is up to speed.

Only it isn’t, not even close. For example, in 2014 Day starred in a YouTube prank that now has more than 22m views. (She masqueraded as the girlfriend of vlogger Caspar Lee, and then hit on Lee’s roommate, fellow vlogger Joe Sugg. The video remains Lee’s most popular by a cool four million.)

Or her ability as a writer: an avid consumer of books, Day had poetry published as a child – in Marks & Spencer of all places – and then graduated to psychological thrillers, until acting got in the way.

Or the juvenile caution for shoplifting. “Primark – I got banned for six months! The irony of it is, the thing I stole was £1.50. It wasn’t because I needed it. It was because I was literally bored and I was hanging out in town with people that were older than me because they were in my year at school.”

She sounds more appalled by the cliché of the offence (Primark!) than the act itself. Day is refreshingly sanguine about past misdemeanours; recognising even the missteps as ground gained on the journey of growing up. “I’m happy I did it, because it moulds who you are as a person. I’ve just got a naughty streak, and I have to get it out.”

Naughty, never malicious. “I’ve never stabbed anyone, don’t get me wrong! I just enjoy taking risks.”

Although she’ll always have a touch of the devil to her – all the best people do – the work will always be sacrosanct. “Because acting means so much to me, I have a really good off button. I won’t speak to my friends for days on end before an important meeting or screentest. I literally switch off. The only way my friends can contact me is via email.”

Even booze is forsaken. “I don’t drink when I’m filming. Ever. Not even a glass of wine at night. I’ve just done a six-month shoot without touching a drop of alcohol. I won’t because I don’t like to risk not doing my best.”

It’s a work ethic that could propel Day to the very top of her profession. Although she has been in the public eye since Hollyoaks, is she prepared for the prospect of wider fame?

I don’t want to be a Bond girl – I want to be Jane Bond. I want to be the first Jane Bond.

“In terms of that bigger scale it scares me a little bit just because I am a private person. I’m doing something to pursue happiness and for the love, not for fame and the money.”

Is it possible to combine recognition and privacy in 2018? “Listen, I’ve done a lot of stuff I’ve managed to keep private!” She laughs. “I’m just going to put that out there! No, I think it is possible. I don’t know. I’d like to think so.”

She can clearly handle herself. Aged 18, Day was leaving a nightclub with a friend when a paparazzi photographer stuck his camera up her dress – a practice which is now illegal. The pap had picked on the wrong women. “We leapt on him! And we made him go through the pictures and delete it.”

It’s a rare anecdote: one that manages to be both depressing and inspiring simultaneously.

Where next for Wallis? Angelina Jolie is an idol: “She made me realise I could have that female James Bond kind of role, that badass secret agent kickass role, and I didn’t have to be a guy to do that.”

When her agent describes a part as very Bond Girl, “I’m like, I don’t want to be a Bond girl – I want to be Jane Bond. I want to be the first Jane Bond. I think it would be so cool to have a female James Bond. I know a lot of people are like, ‘no, it’s a legacy,’ and I totally understand that, and I totally respect that – so maybe make it a spin-off. I don’t know.”

Yet, as Day notes, gender is becoming an increasingly fluid concept – in the film industry and beyond. Why shouldn’t a woman (and massive Bond fan) have a shot at the most famous spy in the world? Especially as she half lives the role – Russian, motorbikes and all.

“Right now, by us limiting genders and races, we’re just limiting ourselves and our creativity. Maybe one day we’ll be able to open up the floor to different possibilities.”

Wallis Day tends to make her own possibilities. Regardless of her next move, success is all but a certainty.

This spring, Wallis stars in SYFY’s Krypton, the Superman prequel TV series. syfy.com/krypton