The Lady is a champ: Why everyone is talking about Jessica Brown-Findlay

Jessica Brown-Findlay has an exuberance that is infectious. The Downton Abbey starlet has been marked out as a star by Bafta, who invited her to the British film event of the year earlier this summer, held in LA, when Prince William and the Duchess of Cambridge pressed the flesh with Hollywood's biggest stars.

As if that were not already enough to enable her to shout from the rafters, aged just 22 she's also carrying a movie for the first time; in Albatross she plays a wayward teen who takes a cleaning job in a Worthing hotel owned by a once-successful writer.

A couple of months on from the Bafta invite, when some of Britain's best young talents met the world's most influential Hollywood players, the sense of excitement is still apparent in her voice. "I was sitting on the plane on the way back, thinking about what had just happened," she gushes in a London hotel. "It was really nice to meet a bunch of people who were in exactly the same position. We were all sitting in the room saying, 'this is weird right, this isn't normal... so you're freaked out about this too?' We don't have to pretend it's run of the mill."

Amazingly, it isn't meeting Tom Hanks or Prince William that she enthuses most over. "We were proper Brits. We stayed up all night and ended up playing a four-hour game of Taboo and getting bloody competitive about it. I thought Bafta would be proud to hear that we ended the night playing a bloody good board game." She ends the sentence with her most plummy accent; a sense of theatre seems to come naturally.

The actor she was most pleased about meeting was Stephen Fry. It's another sign of her down-to-earth nature that it was a British television star rather than a Hollywood superstar who left her tongue-tied. "I basically joined Twitter to follow Stephen Fry." (She herself does not tweet, just observes.) "I kept telling myself to act cool. I failed completely. I didn't even really manage to say hello; it just came out as a weird noise." She also admits to suppressing an urge to ask him to do a scene from Fry and Laurie.

The boot may soon be on the other foot – it could be Brown-Findlay that people are going to be remembering meeting. The ripples that there was a star-in-the-making began as soon as the first series of Downton Abbey aired last year. The first series was set in the two years preceding The First World War and her character, Lady Sybil Crawley, is one of the most forward-thinking, wanting to help housemaid Gwen, and women in general, rise from servitude. The second series has seen the character develop into a more wily soul and her desire to help those less fortunate than her has seen her join Queen Alexandra's Royal Army Nursing Corps.

"She is sort of a heroine in a way," says the actress. "A naive one. She has grown up in a world where she really does believe that things can be done and can be changed. In the second series, that naivety has disappeared a little bit because the reality of war has set in. Obviously, everyone at the time thought the war would only last until Christmas – and as we start two years in, it's clearly not over yet."

In Albatross Brown-Findlay shows that she can play a completely different type of character. Emelia is a sassy working-class girl who comes to work in a hotel owned by Jonathan (Sebastian Koch), a published author with writer's block. She befriends his impressionable daughter Beth (played by Felicity Jones), but this friendship doesn't prevent her from having an affair with Jonathan. Indeed, the only obvious link between the two parts is that they're both coming-of-age roles.

In an age when actors are often cast based on their perceived public persona, it's a smart move to offer two polar opposites as your first roles. This begs the question whether Jessica is more like Emelia or Lady Sybil: "Umm, I don't know," comes the unrevealing response. "I think maybe Emelia is me under a microscope, under a microscope, under a microscope and times a million. I remember stealing some pic'n'mix when I was seven; when I got out of the shop, I burst into tears. Emelia wouldn't think twice about it. She is someone who is very flamboyant and then underneath has a lot going on. I think that is a far more realistic person and that is quite like me."

As for Lady Sybil, who is now proving that action on women's rights speaks louder than words: "Sybil is so good and so righteous and has such a great moral centre. I don't know if I'm so righteous."

As a young girl, Brown-Findlay's passion was ballet. She turned to acting when injury ruled out a career pirouetting. As such, most of her experience of acting has been learnt on the job; much of Downton has been spent observing Maggie Smith et al at work – and learning that it's okay to make mistakes.

One thing that she struggles with is playing angry. "Sometimes when a scene is written or directed to be shouted or played incredibly angrily, I always think it's way more terrifying when someone is fuming and talks in a very calm way. I always want people to shout at me if they're angry – it freaks me out that whole thing of, 'I'm not angry I'm just disappointed'."

I jokingly wonder if that's how she treats her boyfriend, Thomas Campbell, whom she met while studying fine art at Central Saint Martins College of Art. "Poor bloke," comes the equally tongue-in-cheek reply.

To get into the mindset of playing a 17-year-old for Albatross, Brown-Findlay made playlists of music that she listened to when she was 17. "Everything you listen to when you are 17 should be embarrassing, otherwise you are way too cool," she wisely points out. Limp Bizkit and their like have been replaced by Bruce Springsteen, Joy Division and Metronomy; "You have to download their second album, it's insane," she counsels.

Her fingers are adorned with rings; several of them stacked one atop another on one digit. When I comment on them, it leads her to say, "I just really think every job I do, I get this gypsy attitude to money. If I invest in gold it's never going to lose value and if I keep it all on me, if I ever find myself estranged, I can get myself home by pawning it off."

One of the rings, she says, she went halves on with her mother for her 21st birthday present. Her mother, a teacher's assistant, declared it too expensive at first. Her father is a financial advisor and the family home is in the well-to-do village of Cookham, Berkshire. "I think they are a little bit baffled," she says of her folks. "I think they've always thought I was just a bit weird – I used to dress in old clothes and listen to old-fashioned music – but that's fine. My nan and granddad live really nearby and my granddad is a carpenter by trade. He's amazing and my nan is my best friend ever. It's cool. When I was younger it felt like I had two sets of parents."

She admits that she's forever getting told off for being superstitious. "I do so many things. Like when I was younger, if I drove past a house that I didn't want to live in, I'd hold my breath. Driving around somewhere like Slough I'd go blue in the face. Drains! Walking down Old Compton Street in London I don't even have to look down anymore, I just jump occasionally. If you see a big weirdo jumping, that's me. Before I go on stage, I knock three times. Three is my lucky number; I once went into an audition and was number 333 and got the best part ever."

That was back in her dancing days. But for now Brown-Findlay doesn't need to rely on chance; it's her talent, looks and weight of personality that have everyone talking.

'Albatross' is released on 14 October