It wasn’t just the final frontier the South End Green actor had to contend with in the latest Star Trek movie, it was also the weight

When actor Benedict Cumberbatch got the phone call asking him if he wanted to “come and play it?” from the director of the new Star Trek film Into Darkness, he didn’t pick up the signals. It was 2am and he wondered whether he (director J.J. Abrams) meant tennis or squash.

What he meant was did Cumberbatch want to come and play the nastiest role in the film – as mysterious intergalactic terrorist John Harrison, a one-man army of doom?

“Mr Harrison is the grey side of good and evil. He could easily have fallen into a stereotype,” says Cumberbatch. “I oscillated between abhorring him and feeling something for him. In a way, he celebrates ambiguity. He has a moral core with a method that is pretty brutal and horrid.

“I loved the first film (2009’s Star Trek) and spent a day at home filming an audition for the part on my iPhone. By the time I’d compressed the file and sent it, J.J. had gone away on holiday.”

Cumberbatch got an automatic reply saying such and tried to forget about it all and get on with his life.

However, Abrams came back from his holiday and Cumberbatch soon found himself on the set of the Starship Enterprise. It was a set he recalls as being absurdly good fun.

“This is my most physically demanding role yet and, once we’d got over which way my hair would be – straight, curly, ponytail, with bangs or no hair, I had to start to bulk up my body. It meant a lot of eating in a short space of time. It was really hard work. I’d never been asked to do that before.

“They needed me a stiff lump of muscle and I loved it. I ate 4,000 calories a day and turned into a creature from hell! No junk food, just all kinds of chicken, weeks of chicken with potatoes and broccoli, as well as salmon and protein shakes. Later came the hardest part – losing the weight.”

Cumberbatch, is tall with blue eyes, an interesting face and a sort of fruity voice. He’s been called “weirdly fanciable” and a “bit Byronic”. When asked what the 10-year old Benedict Cumberbatch would think of him now, he replies “pretty chuffed”.

“I was probably playing Ann in the school production of Half A Sixpence (Tommy Steele’s musical comedy) when I was 10 and I think he’d be really surprised and wouldn’t quite believe it. I still don’t.”

Sherlock

A slow burner, Cumberbatch, 36, has been around for ages. He is perhaps best known for his portrayal of Stephen Hawking in the BBC drama Hawking and a waspish Sherlock Holmes in the TV adaptation of Conan Doyle’s book. (He is currently shooting a third series of Sherlock.) More recently, we have seen him in the film of War Horse as the necromancer in The Hobbit, in Tinker Tailor Soldier Spy, BBC’s Parade’s End and on stage in Danny Boyle’s production of Frankenstein alternating the roles of the creature and Dr Frankenstein. Up next will be films playing WikiLeaks founder Julian Assange in The Fifth Estate and William Ford in historical drama Twelve Years A Slave.

London-born and South End Green resident, he’s the son of two TV actors, Timothy Carlton (who changed his name from Cumberbatch) and Wanda Ventham. He was educated on an arts scholarship to Harrow where he threw himself into boarding school life.

“It suited me down to the ground. I fell in love with the place,” he says of what he calls the “cashmere jumper” lifestyle. After a gap year in Tibet, he went on to study drama at the University of Manchester and for a while toyed with the idea of becoming a barrister but didn’t.

He tells a touching story about how, when he was 19, he acted in Glengarry Glen Ross and, afterwards, his father said to him that he felt his son was a better actor than he was or ever would be and urged him to make a living out of acting.

For a year, he took a drama course at the London Academy of Music and Dramatic Art and has worked ever since, first as Ben Carlton, changing his mind to go back to his birth name after a colleague mentioned that this name would be a far better way to stand out.

His name, he says, sounds like fart in a bath. “What a fluffy old name,” he comments, laughing.

From Shakespeare to Star Trek, hardly a fluffy old career, Mr Cumberbatch.

Star Trek Into Darkness is out now in cinema. For Michael Joyce’s review, see page 8.