Photography: Rankin. Dress, £1,765, Alexander McQueen; harness, £580, and cuffs, £145, Fleet Ilya; shoes, £535, Camilla Skovgaard

That’s youth for you…

Exactly. I was at drama school and it was the first time I had an awareness of my size and the negative connotations. Before then you experience bullying and whatever, you experience all those things, but you’re not aware that the way you’re born and the way you look could inhibit your opportunities of achieving your ambitions and desires and dreams. I also wanted to challenge notions of femininity and what it is to be a woman. Unfortunately that didn’t happen [with Borland], but it might happen in the future…

You are! Brienne in Game Of Thrones is hardly an archetypal model of femininity.

Yes. It’s really vitally important to me the way women are portrayed. As someone who has always felt at times pretty genderless because of my size, it interests me to challenge ideas of prejudice and femininity and what it is to be a woman. It’s still something that I don’t have all the answers for but I would like to make a bit of a difference; do something, anything, that causes people to have more sense of equality.

Do you find as you become more successful, more public, that you’re judged for what you do? That you can’t just take an acting job with no consequences?

I never wanted ‘a job’. I’m actually far too lazy to ever have ‘a job’. I can’t really see much purpose for me and my own existence other than being in service for an idea that is greater than me. It happens to be that I’m interested in equality and femininity and women. Combining that with my work justifies my existence.

You seem born to play Brienne.

Oh my god, it’s what actors dream of; to find a part that fits like a glove, that you can totally connect with. But also, as we discussed, it’s the most extraordinary opportunity to portray this kind of outsider that hasn’t really been explored much, particularly on mainstream TV.

You say you are lazy but you put a lot of work into changing your physical appearance before you’d even been offered the part didn’t you?

But I don’t think I’ve ever wanted anything as much. I was getting quite comfortable. I was even developing a bust – all those jacket potatoes and bars of chocolate were paying off – and then I lost a stone in weight. I started working out, going to yoga, I completely changed my eating habits and didn’t drink for about two months, just in the service of this part.

Was it incredibly exciting to be able to lose yourself in a process like that?

Not just lose myself but expose myself as well. It was frightening. Imagine; I used to have really long blonde hair, always wearing heels, lots of make-up. I had been someone who was highly feminised and had chosen to look that way, partly because I was 6ft 3in but also I was into that aesthetic. I knew it had to be stripped away. I knew this would be an important part not just for my work but in terms of my own development, because I would be confronting elements of myself that I didn’t want to confront. It was actor’s vanity and personal vanity. To see yourself displayed as unattractive, large, masculine, it’s quite tough… But I know it’s just perspective. A social conditioning that causes us to view these traits in a woman in a negative way, but it’s still hard to watch myself even now.

You’re a huge hit on fan sites and social media. Do you read anything about yourself or the way you’re perceived?

I’ve taken a back step from social media. I don’t think it’s really healthy. I’d rather not know. And it’s completely self indulgent. Although I did tweet yesterday. I tweeted QVC about an item from my friend’s [Giles Deacon’s] jewellery line. [Laughs] I did say I like to make a difference… I’m dedicated to feminism and changing people’s perspectives about prejudice, and tweeting QVC. But as for comments, I couldn’t really cope with anything negative.

I’m going to quote from a fan site now: “I’m very attracted to this woman right now. Very, very attracted. As in I need her in my bed RIGHT NOW.”

What?! [Laughs] Did you write that? Well, maybe as a little treat I might consider it…

How does it make you feel when you hear that sort of adoration?

It’s not me though, that’s the thing, it’s her. It’s Brienne. But that’s thrilling. It’s challenging what’s attractive and what counts as femininity. It’s completely enlightening.

In the books your character continues to have more prominence, so have you signed up on a seven-year contract with HBO?

I don’t think I can say anything. I can’t for a multitude of reasons but also I wouldn’t want to spoil it for fans. Anything can happen…

Especially in the world of Game Of Thrones. In the first few episodes there were seven beheadings, incest, loads of sex; it’s quite a world that you’ve entered into. Do you enjoy the madness of the script?

Oh yes. It’s got so many elements that I love; not just the violence and sex. It’s a brilliant political thriller. It’s full of really extraordinary characters in situations where the stakes are very high, and they’re desperate to achieve what they want by whatever means possible. Plus I just love the blood and guts of it.