Romola Garai is a breath of fresh air in the egocentric world of acting, interrupting our interview by laughing at her answers, and apologising for saying anything vaguely pretentious.

Whether she chooses to deny it or not however, the 30-year-old’s star is still rising fast. I say still, because with films such as Atonement, Vanity Fair, I Capture The Castle and Glorious 39 under her belt, she is already an international star.

But then The Hour came along, hailed as the British version of Mad Men, and the 30-year-old was catapulted even further up the A-list. With the second series currently gracing our TV screens, here and in the US, Romola is now the name on everyone’s lips.

But instead of basking in the limelight, Romola has instead turned her attention to directing. Her resulting debut Scrubber, which she wrote, directed and co-produced, is being shown in a series of ‘shorts’ (The Joy of Six) at Oxford’s Ultimate Picture Palace on Wednesday night, when Romola will be conducting a Q&A session afterwards.

“I can’t wait to come back to Oxford for the screenings because it’s important to get people interested in film and film-making in this country. Plus, the audience gets to talk to someone who knows what they’re doing. Not me, then,” she laughs. “Because I am the only one who hasn’t directed before. And it’s a hard thing to do, so I’m just easing in slowly.”

The acting career must help though? “I never know if it’s a help or a hindrance, because I’ve spent the last 10 years of my life on film and TV sets and I understand the dynamics and know what I like in a director. But on the other hand, I’ve also been critiquing directors for the past 10 years, so I can now sympathise with them,” she pauses and then adds: “I just don’t want to turn into one of those actresses who becomes a terrible know-all. I’d hate to start telling people how to do their jobs,” she says genuinely, “but it’s an amazing skill to learn and something I’d like to do more of.”

Surely this doesn’t mean turning away from her acting career at such a pivotal point? “ Romola smiles: “I’ve always wanted to write, and have never stopped, but rather than just writing I thought it would be great to do some directing and this was the best way.

“But I love my job and I’m not going to give up acting,” she says, aghast at the thought. “And hopefully it doesn’t mean I have to, because lots of people have parallel careers.”

So what’s Scrubber about then? “It’s about trying to be a good mother and how that can be imprisoning and enabling at the same time. It’s quite a visual piece, sorry that sounds really pretentious,” she chuckles. “But it’s also about cleanliness and dirt.”

And it’s got lots of sex, in I hear? “Not lots, but it deals with sexual themes, although that’s not what it’s about. But I can’t give any more away because it’s so short already.”

So what was her inspiration?

“I grew up in Wiltshire, on the edge of a town in a house which encroached into the countryside, so I started with that idea, although the script had many incarnations, but the mother seemed to be the right one in the end,” she sighs, “and it was a very difficult process, but I ended up with something I’m happy with in terms of a script. But I’m not in it and didn’t want to be in it. I would never want to direct myself. I didn’t want that pressure,” she says adamantly.

“I’m just lucky to be involved in projects that have interested me, and as far as I’m concerned that’s hitting the jackpot. You can’t ask for more out of your career. And it would be great to continue like that because there’s nothing more you can ask for.”

Even so, The Hour’s success must have taken her by surprise? “I’m always surprised when people like something I’m in,” she laughs, “but at the same time when I got the job and knew who was in the cast, I knew it would be a good project to be involved in that people wanted to watch. But it’s really nice that people like it.”

And what of the comparisons to Mad Men? “Well obviously they are amazing because Mad Men is arguably the greatest TV show ever made, but I feel quite conflicted about people being nostalgic about them because the whole point of both Mad Men and The Hour is how restricted women were back then, and I want to address that.

“Because yes, Bel might be quite liberated for the period, and I am full of admiration for her breaking the mould, but she makes huge sacrifices to do the things she feels passionately about like having a career, and she has no personal life, much more so in series two when she forfeits any hopes of getting married and having children. So there’s more to it than fashion.”

With so much empathy for her character Bel, is it hard to leave her character behind after filming?

“No, because that’s what we do and then we go home and have a life. It hasn’t changed anything fundamental.

“And besides, there are so many people who start out in this industry really young and then grow along with it, going from job to job. But I’m 30 now and I’ve been acting since I was 17 so you learn a few lessons as you go.”