Just a few years ago, actress Kierston Wareing had almost given up. Back then her career amounted to little more than “a couple of parts in The Bill and a few one liners“. She had even trained as a legal secretary and secured a job as a solicitor’s clerk. That was until she landed a starring role in Ken Loach’s It’s A Free World... and she’s barely stopped since.

“I was a struggling actress,“ the 34-year-old from Essex tells me, sporting a deep tan having just returned from South Africa filming thriller series Mad Dogs for Sky. “After years of nothing I was definitely going to give up.

“If anyone had predicted that I would have been in that film I would have just laughed in their face. I’d been trying this for years. After three months of auditions, I was all suited and booted and ready to leave.“

In It’s A Free World..., for which Kierston recieved a Bafta nomination, her character is hard-nosed and ambitious – qualities found in many of her roles since, like the single mum Joanne in the gritty Fish Tank to sassy detective Lia in The Shadow Line.

As has happened to so many of her characters, when I speak to her, Kierston has a black eye – the result of a bizarre incident in a restuarant near the Mad Dogs set where she walked into a metal bar. “I don’t know how I did it,“ she laughs. “For once the make-up artist was covering it up, rather than painting one on!“

In Four, the darkly comic thriller flick released on DVD next month, her character is battered and abducted but still manages to give her captors an earful. Is she as strong in real life?

“When I need it I can get the strength from somewhere,“ she says. “The more knocks you get in life the stronger you become.“

Aside from years of fruitless auditions, knock-backs, some of the physical kind, littered Kierston’s pre-stardom days. Acting classes and elocution lessons in her youth gave her a voice that stood out at school in Essex.

“I was bullied at school, so I left. Then at the next school, I rebelled and got expelled. I’ve been through domestic violence where the police got involved. I’ve had a string of not very nice men. I’ve suffered violence since I was 14 with my first boyfriend.

“Some people become weaker, I’ve become stronger,“ says Kierston, who is now in a happy relationship and living in east London.

Her determination saw her through many bleak years with little acting work. She did some waitressing, worked at call centres, handed out fliers and even set up a business offering vajazzles – years before The Only Way Is Essex saw the technique popular nationwide. That was all until the Ken Loach appointment changed everything.

“Luckily enough I got the part and it changed everything for me,“ she says. “I put it down to fate. I do believe in what is meant to be, is going to be for you, I believe that in life in general. You’ve got to do something about it, it’s not going to knock on your door, but where you’re going to end up you’re going to end up at the end of the day.

“I couldn’t even imagine now being in an office. I’d hate it! Suddenly it all came along. It’s funny what can be round the corner for someone.“

Four is released on DVD and Blu-Ray on May 7.