Olivia Williams: 'Rufus Norris is like a kid with a box of toys'

I was one of the last actors to do repertory at the Palace Theatre, Westcliff-on-Sea. We actually lived in digs with a gas meter that you had to put 50p in. I was very happy between curtain up and curtain down. To me, the fact I wasn’t being paid anything didn’t matter. I did Agatha Christie’s Witness for the Prosecution, then I understudied Anastasia Hille at the National in Richard III. Ian McKellen was in that. And then I got a break with the RSC, I was in my late twenties by then.

I had eight years away from the stage. I’d been on stage almost non-stop from childhood into my late twenties. When I came back to the National to do Love’s Labour’s Lost I experienced stage fright for the very first time. My kneecap detached from my leg and did a strange sort of dance around my body before I went on. That was quite alarming, an involuntary reaction a bit like vertigo. But it went away very quickly. I hadn’t really questioned whether I could perform on stage until that point. But thankfully I haven’t had the ‘wandering kneecap’ sensation again since.

Mosquitoes is set in 2008 around the very first time that they got a particle to perform a full seven-mile circuit of the Large Hadron Collider. There’s a very good documentary called Particle Fever which follows the events of that day and – in the way Lucy Kirkwood does so brilliantly – she’s written a very human play about the human side of these events, just like with Chimerica, which had an emotional and detailed explanation as to why there was a young man with a white plastic bag standing in front of a tank in Tiananmen Square. It is about the collision of humanity and particle physics in CERN in 2008.

I play a particle physicist and I have a sister who has a very emotional, superstitious, wayward, mystical approach to life. My character’s decisions are all based on proof and empiricism but the sister’s are based on what you can find out on Google and what her friends have told her. The play is about the clash of those cultures.

It’s almost illegal how much fun we’re having in rehearsals. Olivia Colman and I worked together on a film called Hyde Park on Hudson [in 2012] when we kind of fell in love and developed a girl crush. She is an incredibly funny physical comedian. Her access to joy and hilarity is equalled by her access to emotional truth. She covers the gamut of emotion from A to Z. I’m running to keep up, she’s extraordinary.

You should come and see Mosquitoes because you will be transfixed by an extraordinary piece of theatre. It’s very visual and Rufus Norris is like a kid with a box of toys. They’re throwing every single gorgeous modern special effect at this to try and get the audience’s head around two particles colliding in a seven mile tunnel. You’ve also got Olivia Colman and Paul Hilton in a very small room so you can hear the breathing and see the sweat. To see it up close it astounding.

Mosquitoes runs in the Dorfman, National Theatre until 28 September.