The 22-year-old actress at the heart of the BBC One drama The Nest admits that it wasn’t so long ago that she worried about being “too different” from her fellow drama students to make it in her chosen career.

Mirren Mack, who plays volatile teenage mother Kaya in the acclaimed series about surrogacy, says she initially struggled with her feelings about young actors from more affluent backgrounds. “I worried that I might not speak like them and I was a wee bit nervous about how to hold myself in conversations.”

Kaya is only Mack’s second TV part but her performance has been singled out for praise by critics. She stars alongside Martin Compston (Line of Duty) and Sophie Rundle (Peaky Blinders) in the five-part drama that continues this weekend and concludes on Easter Monday.

Although her upbringing in Scotland meant she understood the acting world – her father acts in repertory theatre and her mother teaches drama – she still had some concerns about fitting in.

“I couldn’t afford to simply get on the train the night before an audition and stay in a hotel,” she said. Instead, she would take a night bus from her home town of Stirling to London. “You get a bed on the bus and a muffin. I’d get on at 11pm, get into London at 7am, get changed in Starbucks’s toilet, go and do the audition and then get the bus back.”

She went on to win a place at the Guildhall School of Music & Drama and was able to attend thanks to a number of bursaries and scholarships.

I worried I might not speak like the other students and I was a wee bit nervous about holding myself in conversations. Mirren Mack

“I [later] realised that people’s lives can be both amazing and difficult, no matter where they come from, but I do find it interesting that me and others had to sort of rely on the kindness of strangers to get where we were, whereas some people could do that for themselves or thanks to their family’s money.”

Mack got the part in The Nest while still at the Guildhall and has also had a small but key role as the asexual Florence in the second series of hit Netflix show Sex Education. She has since been cast in The Beast of Blue Yonder, the latest play from award-winning writer Philip Ridley. Its opening at Southwark Playhouse has been postponed because of the pandemic.

She describes acting opposite Gillian Anderson in Sex Education as “jaw-dropping”. “My heart was going so fast during the scenes with her – I did have to keep telling myself ‘remember to act’.”

She was thrilled, too, at the positive online response to her asexual character. “I hadn’t realised how little representation of asexuality there is. I did do research but the best thing was getting feedback from people who said that they had actually found themselves in a storyline.”

It is The Nest, however, which looks set to propel Mack into the big time. Created by Nicole Taylor, the award-winning writer of Three Girls and country music hit Wild Rose, it is a tense drama about class, privilege and the question of who deserves success in life.

Mack was delighted that her first major role had taken her back home. “One of the things I loved most about filming it was that it was a beautiful showcase of Glasgow,” she said. “There’s one point when I’m on a rooftop looking out over this amazing city. It was really emotional because this part of Scotland is so rich with life and I’m standing there after a couple of years at drama school, finally doing what I love more than anything else in the world, here in this place that I also love.

“I was such a mess that I actually started to cry.”