Gemma Chan is nervous, as if she’s waiting for the dentist to perform a particularly painful extraction. We meet in a café filled with babies and tired-looking mothers, in a fancy, rich-people part of north London. The setting is appropriate, given what we’re here to talk about: I Am Hannah, the new improvised Channel 4 drama she co-created with director Dominic Savage. It tells the story of a woman in her mid-30s who dates, scattershot, via apps, while feeling the weight of the biological and social pressures to have a baby. Chan, 36, is keen to point out that it is not autobiographical.

“I mean, God. I have friends who are so happily married with children, on their third, some friends who’ve done it who are struggling with elements of it, and other friends who have no interest in it, are free and single.” She inhales sharply. “Yeah. It’s weird. I do find it strange that in your 30s, suddenly, you become more aware that, if I’m going to do it, try to have a biological child, I need to think about it now.” She clams up. “Sorry, I don’t have anything to add to that.”

It takes a while for her nerves to ease. “People don’t believe it,” she says, “but I’m naturally quite shy. I’ve had to work really hard to mask that, not appear anxious or nervous.” Red carpets are tricky for her, even now. She always worries she’s going to fall over. “And I’ve nearly fainted before, because you don’t realise you’re not breathing and all of the flashes start going off in your face, and I’ve started to…” She mock-swoons. “Imagine!” To deal with it, she puts on a character, her own version of Sasha Fierce, Beyoncé’s alter ego. “In character I feel like I can do anything, really. That’s part of what attracted me to acting. But if you ask me to make a speech as me, I find that so difficult. I hate my own birthday, I hate being the centre of attention.”

‘In character I feel like I can do anything, but I’m naturally quite shy’: with Lisa Lu in Crazy Rich Asians. Photograph: Everett Collection/Alamy

Given the level of Chan’s recent success, she may have to start getting used to it. After slowly beginning her career in British television, she has hit Hollywood with a vengeance, playing Minn-Erva in Captain Marvel, which required being at work before 3am for four hours of hair and makeup, as her character was entirely blue. She was Bess of Hardwick in Mary Queen of Scots, and Madam Ya Zhou in Fantastic Beasts and Where to Find Them. Then there was Crazy Rich Asians, which cemented her status as an international star when she played Astrid, an elegant, ultra-wealthy socialite whose surface perfection covered up a hidden pain.

I’d be on a set and not only would I be the only Asian, I’d be the only actor of colour

For someone who is so reticent in interviews, so reluctant to give anything away, Chan hints at a rebellious side that doesn’t come out much in public. She’s “quite lazy,” she says and “I definitely have always been fly by the seat of my pants. If I can leave things until the last minute, I will.” She was not always well behaved at school, she claims, and she has never liked authority. Has that carried through to her adult life? “Err, yeah,” she laughs. “Yes. Oh, God.” But she won’t tell me how. “There’s just a little bit of a naughty side. Everything I can think of is either lame or I can’t say it.”

Perhaps there’s an indication in what happened to her at this year’s Met Gala, where Tom Ford dressed her in an Elizabeth Taylor-inspired look, adhering to the camp theme perfectly. “That whole experience was so surreal,” she says. “You’re in line, and literally every person around you, it’s like being in Madame Tussauds. I had Joan Collins on one side, Kim Kardashian and Kanye in front of me. Gwyneth just there. They’re all talking to each other, because they know each other, and you’re just standing there going, this is mental.”

When Chan went to her hotel to change into her second look, she found herself on a bus back to the afterparty with Celine Dion. “She was an absolute fucking legend,” she says, happily. “It was me and her and her dancers, just dancing on this bus. It was the best half an hour of my life.” There is a video, but she vows that it will never be seen. “I can’t believe it happened. Nothing will top that. I pole-danced on a bus with Celine Dion.”

Was it being part of the Crazy Rich Asians phenomenon that led her to the point of riding on a party bus with Celine Dion? “I think that’s fair to say, yes,” says Chan. “I look back on it now and I couldn’t have imagined that film being made, even five years ago. I feel so lucky that I was a part of it.” She pauses. “And not to overhype it or overegg it or anything, but I took my mum and dad with me to the premiere in London, and they were just in tears. My mum said to me, she never expected to see people [on screen] who looked like her family, the food that we ate, music that was in the soundtrack that she hadn’t heard since her childhood. It was really personal and really special.”

‘Emotionally raw’: as Hannah with Arinzé Kene in Channel 4’s I Am Hannah. Photograph: Aimee Spinks/Channel 4

Chan grew up near Sevenoaks in Kent. After school, she studied law at Oxford University (she chose Worcester College because it had an even male/female and state school/private school split). She eventually won a job at a law firm, but deferred the placement for two years in a row before finally turning it down to go to drama school. “I realise that what had initially attracted me to law was watching films that were courtroom dramas and barristers giving these amazing speeches,” she laughs. She says she just hadn’t known it was possible to be a professional actor.

Telling her parents she was going to pursue acting and not law was difficult. “I knew how important education was because of my parents,” she says. “It’s what got my dad out of poverty, enabled his siblings to, and it meant he could come to the UK.” It made the decision hard. “It was really, really painful. I hated that. I hated causing them pain.” They did not take the news well. “I feel bad for talking about it now because they’re so proud and supportive. But I totally understand where they were coming from. It was a pure fear of not knowing whether I was going to be all right. Both my parents are immigrants. They came from nothing, had to work so hard, and so the idea for them, I suppose, of taking a risk, that wasn’t a luxury they had. I always knew that was the luxury and privilege that I had, that they had given me.”

When Chan left drama school, one of her teachers told her she might find it difficult to get acting jobs. I ask if it was meant kindly. “Erm,” she says. “I think it was meant well, but it was also said quite bluntly, as well. In a way, they were right. At that time, 11 years ago, there were very, very few opportunities on British TV if you were an actor of colour and the logical thing would have been to go to America.” The teacher had told her that she’d have more of a shot if she crossed the Atlantic. “But I really wanted to try and make it work in the UK. I wanted to give that a chance.”

Dress rehearsal: with Tom Ford celebrating the opening of Camp: Notes on Fashion, Arrivals at the Metropolitan Museum of Art, New York, in May 2019. Photograph: Ovidiu Hrubaru/Rex/Shutterstock

I mention a recent interview with Idris Elba, in which the actor was asked about race, and he said, “I don’t think we’ve turned a corner until we don’t have to talk about it.” Chan says she gets where he’s coming from. “The ideal place would be for it to be completely normalised and not a big deal. And I feel like we’re working towards that, in all different kinds of areas, not just to do with race, to do with sexuality, gender, body type, body size, everything. I feel like we’ve made huge strides in the last couple of years.” She laughs. “But I’m really looking forward to the time when I no longer have to answer questions about race.”

I’m still adjusting to life in the spotlight. I don’t know if you ever become at ease with fame

Recently, Chan was invited to become a member of the Academy of Motion Picture Arts and Sciences, which means she’ll vote for the Oscars. “I mean!” she exclaims. “That’s bonkers. I wasn’t expecting it at all. I found out when everyone else did.” She was getting texts of congratulations and wondered what she was being congratulated for. “It’s strange, it’s incredible, but it also doesn’t feel quite real, because for so long, I suppose, I’ve always felt slightly… I guess the Academy is the establishment and I’ve definitely never felt like that. Am I part of the establishment?”

I think this means she is now, yes. “Oh God! Oh that’s terrible,” she laughs. I ask her why she feels as if she’s still an outsider. “Well, for one, most of the time, I’d be on a set and not only would I be the only Asian, I’d be the only actor of colour. For the longest time.” She is wary of sounding like she’s complaining. “Because I also feel like I’ve been incredibly lucky, to be able to work and make a career out of it. But definitely at the beginning, there was nothing out there that was remotely a good part that I would be able to audition for. I wouldn’t be called in for anything that was a lead role.” She decided she needed to get as much experience as she could. She took everything she was offered and built up her career, small part by small part. “I knew it wasn’t going to be handed to me in any way. I suppose that’s what I mean.”

For a while, Chan was a tabloid regular, in part because of her years-long relationship with Jack Whitehall, which ended in 2017. (Today, she firmly but politely says she’d prefer not to talk about her personal life.) With her shyness and her reluctance to give much away, she does not seem particularly suited to that side of the spotlight. “I’ve never ever bought into it in any way. I’ve also seen people really struggle with it, so I’ve never really had any illusions.”

Acting up: as Bess of Hardwick in 2018’s Mary Queen of Scots. Photograph: Everett Collection/Alamy

She starts to stumble over her words. “I’m still adjusting, basically. I don’t know if you ever become at ease with it.” She mentions a trip to Singapore, to promote Captain Marvel, and how shocked she was to find that, in the wake of Crazy Rich Asians, she couldn’t walk through the airport. On the other hand, she reasons, she does understand what it means to be a fangirl, to have those moments of awe. “Like, Lucy Liu, I’ve run up to her and gone, ‘I love you,’ and she’s looked at me like, you’re insane. I’m like, oh my God, I can’t believe I just did that. So I totally get it.”

It’s early on a Friday evening and the café is starting to empty out. Chan can’t talk about the films she’s doing next, because they haven’t been announced yet, but there are two of them, and they’re happening soon. She has set up her own production company, so new it doesn’t have a name, and she is developing stories about “a lot of women who never got their due in their time, who weren’t appreciated or recognised, but now we look back and think my God, they were amazing, they were pioneers.” I ask her who, but she just smiles. “I don’t want to say, because I’m developing a film around that person.” Tonight, she’s going to meet some friends for a drink. “And take it easy, and just relax,” she says, actually looking relaxed, at last.

I Am Hannah airs on 6 August at 10pm on Channel 4