Eddie Redmayne was joined by Stephen Hawking tonight for the premiere of The Theory Of Everything, in which he plays the physicist.
Oscars-tipped actor Redmayne stars in the film alongside Felicity Jones as Hawking's first wife Jane, in the tale of their early relationship, Hawking's first steps in his career and his diagnosis with motor neurone disease.
Redmayne admitted that despite having crossed paths with the professor as a student at Cambridge, he still felt starstruck at the prospect of playing him.
He said: "I'd been a student at Cambridge and seen Stephen across campus, heard his voice, but I was pretty ignorant so when I read the script, everything was a revelation.
"Stephen and Jane let Felicity and I into their lives, so we felt an enormous amount of responsibility to get it right."
Jones added of taking on a real life character in Jane: "My instinct was when you're playing a real person you want to get that person's blessing and that's just building up trust with each other.
"Jane is incredibly open, she showed me photos of her and Stephen when they first met and I really felt I was getting this glimpse into an intimate side of their lives.
"Stephen and Jane have this wonderful unsentimental approach to life and such wit, so wherever we could we wanted to put that into the film."
Talking about suggestions of Oscars nods for both the film and his role, Redmayne said: "I try not to listen to buzz because it's a fleeting thing and if you listen to the good stuff you automatically take on the bad stuff, so I try to put my fingers in my ears and just keep putting one foot in front of the other."
Jones added: "It's really exciting, it is a film we cared so much about and the fact that people are responding to it is wonderful, that doesn't always happen."
Joining Hawking, Redmayne and Jones on the red carpet at the film's premiere in London's Leicester Square were Jane Hawking, director James Marsh and co-stars Maxine Peake, David Thewlis, Harry Lloyd and Simon McBurney.
The Theory Of Everything is released in cinemas on January 1, 2015.