I've been very lucky at what's happened in my career to date, but playing something as far from me as possible is an ambition of mine - anything from a mutated baddy in a comic book action thriller, to a detective. If anything, I'd like Gary Oldman's career: he's the perfect example of it. I've love to have a really broad sweep of characters - to be able to do something edgy, surprising and unfashionable.

I'm not one for doing the children's party version: "Hi, I'm a character in a movie and now I'm in reality!" I was doing the last shot of the film before reshoots outside their shop. I was starting my run into the frame and I thought, "You are literally ending where this began. The loop of serendipity's too much to not go in and acknowledge it." I just wanted to see the look on their faces.

I wanted to take the audience on a journey where that transition was funny and awkward. It's the same cynicism that [Strange] has.

My assessment of Julian Assange is a professional one, really, of what he's managed to achieve, and the idea that he came up with, which set the world alight and continues to inspire others like Snowden [NSA leaker Edward Snowden], about the secret goings-on that are done in our name with our tax dollars on behalf of big business or politics. He launched the revolutionary idea that citizens can start to claim back a paradigm for questioning power structures and those in authority through an anonymous, whistle-blowing website.

It's an interesting arc. You start with a character [Doctor Strange] who's likeable and charming but very arrogant and distant. He's funny but you can see there are massive holes in his life. It's a very painful transition and all that he becomes is tested so quickly and violently.

I had to imagine myself into certain aspects of [Julian Assange] character for our version of events. That involved extrapolating based on clues in his biography, his public persona, photographs, and other accounts of him by people who encountered him during that extraordinary period from 2007 to 2010 that we charted in the film [The Fifth Estate]. So, it involved a lot of research but, sadly, no contact with the man himself.

I was never geeky about anything.