As she takes on a lead role in the TV adaptation of Kate Mosse’s novel Labyrinth, Jessica Brown Findlay talks to Sophie Herdman

IT'S the most common observation in the book – that an actor is much smaller than you imagined. But with Jessica Brown Findlay this really is true. It's obvious the moment the ex-Downton Abbey star bounds into the room and sinks into a large armchair.

But what 23-year-old Brown Findlay lacks in size, she certainly makes up for in personality. She speaks in a considered and intelligent way and firmly bats away any vaguely controversial questions.

Like when she is asked how she felt about appearing naked in her new TV show, Labyrinth.

"It's a fleeting moment and that's it," she says of her first scene, in which she arises unclothed from her marital bed.

"She's a married woman, it's medieval times and this scene is much more about an introduction to a couple."

But even with her body so exposed she didn't feel the need to work out for this role – or for any role as it happens. "Maybe it is part of the job, but I don't. Obviously being healthy, that's just a common sense thing."

Brown Findlay is a fan of imperfections – be they in a character or the actor playing a role. "Seeing on-screen perfection that can only be achieved by having a dietician and working out all the time - I don't understand what kind of message that gives out, especially to young women. Perfection is unachievable."

In fact, it is imperfections that she looks for when deciding whether to go for a role, saying: "They make characters jump out and are much more exciting to play."

Which brings us neatly on to Alais, her character in Labyrinth – a strong, bold but naive woman on the search for the Holy Grail. The two-part series is based on the book of the same name by Kate Mosse, and parallels Alais's search with that of Alice, a modern-day woman who finds herself in France.

"Alais's life starts to crumble and then she's handed this responsibility – it becomes the making of her."

The character's determination not to be held back by fear is reminiscent of Brown Findlay herself, who made the bold decision to leave Downton Abbey, in which she played Lady Sybil, because she wanted a challenge.

"Facing the abyss of the unknown is just so exciting. What scares me more is staying comfortable," she says.

Taking on a leading role in Labyrinth was no easy task – the book was a bestseller in 2006 and translation rights have been sold in 38 languages. Did she feel a lot of pressure?

"I suppose there was a certain aspect of that, but it's more in retrospect having done the job," she says. Having Mosse on set (the author came to visit during filming) was a positive, she adds.

She keeps in touch with the Downton crew. "My sisters I love to pieces, we get on like a house on fire. It's corny as hell to say it, but it was such a lovely family."

But she's got plenty to keep her busy now she's left. Next she's starring in a film adaptation of the Mark Helprin's novel Winter's Tale, alongside Russell Crowe and Will Smith.

Unlike many actresses who are scared to use the f-word, Brown Findlay says she is a feminist. "It's just an equality issue. People hear the word feminist and think you want to burn your bra. But I like what Caitlin Moran says: 'I love my bra, it's brilliant, I couldn't live without it'."

So far fame hasn't affected Brown Findlay's life. She doesn't get recognised on the streets and puts that down to the difference between the flawless period drama version of herself and her everyday look. "But really," she says, "I just don't think people expect to see me in Tesco looking for loo rolls."

Labyrinth is on Channel 4 on Saturday, March 30 and Sunday, March 31.