Sherlock's lovelorn Molly on feminism, being proposed to 18 times on Twitter – and what really rings her bell

Judging from your recent tweets, you had quite a riotous time at the Radio Times party last night?

Oh God. I think I use Twitter almost like I'm talking to myself and then forget people actually read it. The party was so much fun. They don't give you any canapes. It's a trick to get you absolutely twatted. I ended up in the Groucho club in the wee hours, assaulting someone for not wanting to marry me. Today I'm feeling poorly, a bit weak. I'm drinking Lucozade.

Is that your hangover cure of choice?

If I could get Irn-Bru, I would have got that. But this is the same colour, so psychologically it's the same.

As well as being an actress, you're also a published journalist, have edited a book on film and are currently producing and writing a series on Dickens for the BBC. Are you a bit of an overachiever?

Am I? I think it's just suddenly all of the three things I do have come together at once and it's slightly alarming. I'm really shy about being interviewed because I used to interview people. It's like I have a little parrot on my shoulder going "Oh God, what have I said? It won't translate..."

You're most famous for playing the lovelorn Molly in the BBC drama Sherlock. Did you expect the show to be so successful when you signed up?

The reaction to Molly this series has completely taken me by surprise. I did my day or two filming, like last time. But this year - because of the frankly brilliant writing - I think people have noticed her. Which is amazing. Molly works because, while Watson is "the audience", Molly is every woman of a certain age sitting at home on the settee fantasising about running their hands through Benedict Cumberbatch's hair. Which is basically what I'd have been doing if I wasn't in the show... Also, I think most people have experienced the agony and the ignominy of unrequited love... I've never thought Molly was an idiot. She just really, really loves him.

Will Sherlock ever return her affections?

I think it's unlikely, don't you? I don't think she's really his type. What his type is, I don't know.

You read history at Cambridge. What was your favourite period?

I was a complete dilettante with history. I jumped around willy-nilly from one period to another. The paper I fell in love with – which was possibly quite a lot to do with falling in love with the history tutor who wore a leather jacket and chain-smoked and was gorgeous – was ancient political thought. Aristotle and Plato and all that. I loved it. I got a first in that paper because I was suddenly quite excited about learning.

After university, you trained at the Lee Strasberg Theatre and Film Institute in New York and studied with "clown guru" Philippe Gaulier. What exactly is a "clown guru"?

[Laughs] Well, Philippe's basic philosophy was: if you have pleasure to be on stage, we have pleasure to watch you... Even if you're playing a tragedy, you have a kind of game with the audience, it's a twinkle.

You describe yourself as a feminist on your Twitter biography. What kind?

A militant one. Dungarees, moustache, all men are rapists, you know the drill... Seriously, though, I'd like every man who doesn't call himself a feminist to explain to the women in his life why he doesn't believe in equality for women. I think Page 3, Nuts and Zoo are bullshit. I don't wax my pubic hair off. I don't think working in a titty bar getting fivers shoved up your bum is empowering. And I'm bored of pictures of women in their smalls on buses with fuck-me mouths.

Do you like Twitter?

Twitter's amazing because suddenly being on the telly is like being on stage: you get this immediate response and it's really unusual. On Sunday [when the last episode of Sherlock aired], it was extraordinary. I got hundreds of messages and 18 marriage proposals.

Eighteen?!

Yes, mostly from young women. There's this whole world of fandom. What's fascinating is that they [the fans] write these stories about the characters. I initially thought they were just stories but they're not; they're basically porn.

After the first series, I was looking online to see what people thought of Molly and what came out was this story in which Molly got nipple piercings and had sex with Moriarty. At which point, I stopped reading.

When you interviewed the actress Liv Tyler in 2009 for Wonderland magazine, you asked her whether there was a consistent theme running through her school reports. Was there one in yours?

Erm, my school reports vacillated wildly for years and years. I used to be a complete goody two-shoes but when I was in the sixth form, I came off the rails because I'd been at a girls' school and I was excited about being with boys. I was doing a lot of skiving and was put on report for a while. That's about as cool as I got as a child.

On your website, you say you like campanology...

Yes, when I was 14 I became religious. I went to church off my own bat. It was something to do with a cat being run over but it's too embarrassing to say why. For a couple of years, I was very excited about church. I joined up for the bell-ringing... It's quite exciting because you could be whipped up to the ceiling and have your neck broken.

I used to be on the littlest bell, on the treble, and there's a magic moment where you're just pulling down a little bit and the bell is balancing; it's not resting on anything. It's a really amazing feeling.

Sherlock series 2 is out on DVD now