It's fair to say Jessica Brown-Findlay makes an impression when she first appears in her new film Albatross.

It’s fair to say Jessica Brown-Findlay makes an impression when she first appears in her new film Albatross.

Asked by a shopkeeper to prove she’s old enough to buy the bottle of wine, she gives him a look, pulls up her top and flashes her breasts. This afternoon in Edinburgh the actor is a little more demure. A shy hello and a quick handshake is all I get. Well, it is Sunday and I haven’t got any wine to hand.

No, she tells me, that film scene apart, she has never, as far as she can recall, flashed at a shopkeeper or anyone else for that matter. This is just one of the many ways she is not like the character she plays in the movie.

I know. I know. Hardly a great revelation: “Actor not exactly like character she plays.” But Brown-Findlay is so good in the film that meeting her inevitably leaves you gasping a little at the gap between the screen and real life. In Albatross, Brown-Findlay plays Emelia, a troubled, troublesome 17-year-old wannabe novelist who juices up the life of straight-A student Felicity Jones and her family (mainly by sleeping with the father, played by Sebastian Koch). When she was 17, Brown-Findlay (now an elderly 21) tells me, she was much shyer. “Some elements of Emelia are me with a magnifying glass times 10. I was not that outrageous, boozy girl at 17. Definitely not.”

What she is is pretty, pretty young and pretty excited about being in Edinburgh, the city where her grandmother was born, for the premiere of Albatross. She’s dressed up for her photos in a skirt and high heels (how high, I ask. She’s not sure). If Albatross is anything to go by -- she’s by far the best thing about the movie -- dressing up for photoshoots will soon be commonplace.

Of course if I lived anywhere in Britain other than Scotland I might already have known all about her. Since making Albatross she has appeared in that rare thing, an ITV drama success, Downton Abbey, which was huge everywhere but here (though STV is showing the second series). Did she know it was going to be a hit when she was making it? “To a certain extent,” says Brown-Findlay. “At the end of filming last year the cast went out for dinner and there was this feeling in the room. It felt special. I think at that point we thought: ‘This could be really good.’” But good would have been four or five million viewers, enough to get it recommissioned. “None of us expected 13 million people to watch it. That’s just ridiculous. That’s old-school ratings. Christmas specials.”

More importantly, Jessica: corsets. Good or bad? “Bad. Although if we wore corsets now there would be no need for fancy push-up bras or anything going on there.”

In Downton she plays Lady Sybil Crawley, the bolshie youngest daughter of an aristrocratic family (the other end of the class scale to Emelia). She dismisses complaints that it’s a Tory drama, half in love with the upstairs-downstairs lifestyle it portrays.

“It does comment on class -- it’s silly to say it doesn’t -- but the thing it’s really saying is that we don’t change at all. Things that fascinate us now fascinated people then. People falling in love. Jealousy and anger. All that stuff is universal. A lord can just be as head over heels as a scullery maid.”

Given the part, the double-barrelled name and the fact that before she wanted to be an actor she wanted to be a ballerina, you could jump to the conclusion that Brown-Findlay herself is from the other end of the class scale to Emelia. But that would be to confuse the actor and the role again.

Truth is she grew up in Cookham in Berkshire with “pretty normal parents”. Her mother is a teaching assistant and her father a financial adviser. “He hasn’t given me any financial advice,” she adds, laughing. “I think he wants me to pay him.” She’s got a younger sister. Oh, and she went to a comprehensive school.

What else do you need to know? She got drunk for the first time at 13. “On what? Probably a WKD. I remember me and my friend Naomi went upstairs to her bedroom and found a dressing-up box and we came down and I was dressed up as Little Bo Peep.” She fell in love for the first time at 14. Well, a 14-year-old’s idea of love, perhaps, but “the first time I said ‘I love you’ I was 14”. And did he say it back? “Yes. My childhood crush all the way through school, so that was nice.” They lasted a year together and then he dumped her. “I was heartbroken. Heartbroken!”

In the end he couldn’t compete with the one thing she loved more. Ballet. “I started when I was two and a half, just baby ballet. I saw a girl in my nursery come in a little pink outfit. And I was like, ‘Mum, what do I have to do to wear that?’ Just loved it. And I was really disappointed that my ballet school wore blue not pink.”

She still went, though. When she was nine or thereabouts she announced to her parents she was going to be a ballet dancer. “But I was always very conscious that if I was going to do it I would have to be good because my parents couldn’t afford to send me to ballet school or pay for loads of lessons.” So she aimed for scholarships. And got them. “I would never have been able to train to the level I did without that support.”

She attended National Youth Ballet, did summer schools, became a Royal Ballet mid associate and then senior associate, as well as a London Junior Ballet associate, which meant training would start at seven in the morning at weekends and end at six in the evening. “During the week my ballet teacher ended up giving me lessons for free.” And after ballet lessons Brown-Findlay would study for her A levels. Did her schoolwork suffer? “No,” she says. “It’s an odd thing. I enjoyed school so much and I enjoyed learning. I’ve always been inquisitive. My mum had to come in at night and unscrew the lightbulb. I was a big geek. I think I’m still quite geeky.”

Has the word precocious come to mind yet, reader? Well, maybe, but then the point is Brown-Findlay’s sweet monomania is just as typically teenage as rioting hoodies. Anyway, the unfortunate thing is it didn’t last. And not out of choice.

In her mid-teens her ankles began to ache. When it first started she tried to ignore the pain. “I knew an injured dancer is not what you want. I was at my ballet school on a full scholarship. ‘Oh my God. If I can’t dance I’ll have to go back home.’”

So she tried to carry on. But the pain continued. She was suffering from heel spurs, extra bits of bone on the ankle joint. In her case they were attached rather than floating. “So they had to go in and shave them off. I did two at once. The right one worked perfectly and the left one didn’t. We went in again on the left and it just didn’t work. An ankle joint is so small and there’s so much going on in there and it has to be the most mobile part of your body. And the strongest part. And at that time of the game -- at the very end of training, at the point of auditioning for ballet companies -- it’s not the time to not be able to dance for three or four years. And I just had to move on.”

Does she remember being told she wouldn’t dance again? “Yeah. It was very weird. I felt numb.” The specialists at the hospital had explained what had happened to her at the hospital but she hadn’t really taken it in. It was only when she was sitting in the head of dance’s office that reality bit. “She just said, ‘This will never work. You won’t be able to dance.’ I almost didn’t feel anything because I didn’t know what to feel. I’d never prepared my head for that.”

Brown-Findlay went into autopilot afterwards, she says. She concentrated on her exams, blocking out what she had lost. She applied for art school and went off to study at Central St Martins, and it was only when her friends began to dance professionally that it really hit her. “I was one year into art school and my friends were starting to perform and posting pictures on Facebook of themselves training, and I thought, ‘Oh my God, that’s never going to happen …’”

There was the odd upside. “The physical pain I could do without.” (She remembers preparing for one assessment with only four toenails left.) But she found she missed the rush of performance. That’s what she rediscovered in acting. “The sort of forgetting what you’re doing and it just coming out of you. That’s almost how it feels when you’re acting. You almost forget anyone else is in the room and someone shouts, ‘Cut,’ and you’re a bit unsure why they said it. That is what I missed and what I craved.”

She says she grew up on the set of Albatross. “I feel like I went a girl and came back a woman. I really fell in love with the job. Being given that responsibility and having the sense that people had faith in you is the most liberating experience. I came back and sort of felt grown up. I always used to think it would be awful if someone described me as a woman. I’d be, ‘No, I’m a girl. What are you talking about?’ And actually it’s a huge compliment.

“Don’t get me wrong. I’m a complete idiot. But I came back being a bit more comfortable with myself and thinking it’s OK to not know anything because nobody does. Everyone is making it up as they go along.”

Jessica Brown-Findlay lives in a basement flat in London -- but not with her boyfriend -- in a room full of pictures and drawings and paintings. She would love to make a movie with Sofia Coppola and Maggie Gyllenhaal. She’s not sure whether older men are a good or bad idea. “My boyfriend is younger than me.” Yes, by a month. “But he reminds me of it all the time.” She’s not very tidy, she likes a pint of Guinness and loves music. The last time she danced? “When I was getting ready today. I was dancing around to The Libertines.” She used to wear hearts on her sleeves -- as in heart designs, not real ones -- as a warning to everyone that she does tend to wear her heart on her sleeve (“I can’t do cool, calm and collected”). She doesn’t feel the need to be successful as much as the need to be happy. Is she good at enduring pain? “Enjoying pain?” No, Jessica, enduring pain (what kind of man do you think I am?). “Enduring pain? Yes, I think so.”

Tomorrow she will jump in the hotel’s swimming pool and muck around. She may not be a girl any more, but she still likes to play. Emelia would approve. “I think by playing Emelia I ended up taking a bit of her back -- that kind of go-get-it attitude and that fire and guts about her. I’ve kept a little bit of that, which I think is a good thing.”

It’s time to get ready for her premiere. Time to introduce herself to the world. Flashing will not be required.

Albatross (15) goes on general release on October 14. Downton Abbey, STV, Sundays, 9pm.