“She is absolutely adorable, lovely… She wants to help,” is Christopher Oram’s verdict on Nicole Kidman. Not that I’ve met many, but anyone who can make any personal comment on Kidman – and in such an oh-so-chill manner – seems pretty impressive to me. Yet Oram is personable, practical and laudably aware of how lucky he is to be an award-winning designer.

Not that he hasn’t worked hard to achieve his Olivier Awards and Tony Award, among a dazzling array of others. For Oram, to be a theatre designer, or anyone at all who works in theatre, you have to “be interested in it. Don’t do it half-heartedly. You have to go to the theatre. You have to eat, sleep, live, breathe theatre. You have to want to be in this industry. At the end of the day, it’s too weird and too much hard work to not want that. More importantly than that, there is no such thing as ‘oh, I can’t afford it’. There is always theatre any night of the week that you can get into for £10 somehow, somewhere.”

Theatre design, Oram admits, isn’t something a typical five year old aspires to be. Oram grew up enjoying that same slice of theatre as most people: musicals, pantomimes and, occasionally, something more. It was only when he attended art school, experiencing everything from painting to culture, that he realised he was most interested in sculpture and physical form, and that, for him, “interacting with space was the most interesting thing. Theatre became a kind of extension of that…You realise the potential of it: working in space, working with performers, working with light and sound.”

Theatre design is often invisible to an audience and yet – more than a script or acting – it can immediately influence an audience’s mood. Everything is artificially created. “Far beyond ‘what a pretty set’,” which is the normal audience reaction, “you have a lot of influence in terms how the evening is received. Subliminally, without people even realising it”.

“I absolutely believe in theatre as a collaborative form,” says Oram. His rapport with Kidman is just one example of the many interactions crucial to a theatre designer’s job. “All the best ideas in the world mean nothing if there’s no money or –worse than that – if there’s money, but there’s no time to do it or no space.” He gives the example an actor refusing to wear their costume. I scoff, revelling in the stereotypical pouty and spoiled actor. “Well, sometimes they’re right,” Oram counters. “A lot of people know their bodies more than someone looking in from the outside… but sometimes you do know better. You know, ‘trust me, you don’t look good in those pants’”.

More than anything, Oram adapts to the play. From Shakespeare’s lack of stage directions to “George Bernard Shaw’s 25 pages on what cufflinks someone is wearing…Part of the brief is to make sure the design works for the play. And that might be stripping it back to the absolute bare essentials, very minimal and simple. Or it might be doing detailed naturalism that people take for granted. People don’t see naturalism on stage. They think ‘there’s a room’, but don’t ever consider that someone’s put that room together.”

“The older you get, the more you have to diversify in order to develop”. This is why Oram couldn’t say he has a particular style. The longer your career, the more theatrical styles you discover, and the more your style changes in turn. “I’m not on a factory line screwing a head onto the same doll…You read something and you have a response to it… Generally I find that my first response is what ends up on stage.” Some plays you accept for the people or the places rather than the script, but Oram ends up “loving them all. But some particularly sing out” to him.

Working with his partner Michael Grandage must make a play particularly “sing out”. Working on their current project Photograph 51, which tells the story of the extraordinary contribution to genetics of Rosalind Franklin, professionally reunites them after two years. It was “like putting on a comfy pair of old jeans…. I’ve done a lot of work with people in the meantime that has been rewarding and exciting and challenging… and horrifying…. But I know Michael’s taste, I know what to do.” What’s more, Oram thinks his Photograph 51 suits “his style of direction and my style of design”.

Despite – and perhaps because of – its scientific story, Photograph 51 is a very human play, and “rights the wrongs we’ve done to Franklin since she died 50 years ago, not recognising the massive contributions she made to the discovery of DNA…” Photograph 51 will do for an audience what it did for Oram: open up a new world. When researching the play, one person he met “was so impassioned about his art of science. He was practically moved to tears when he described it… Passion is everywhere, which is wonderful”.

Photograph 51 is playing Noel Coward Theatre until 21 November. For more information and tickets, see http://www.noelcowardtheatre.co.uk/.