'I thought I'd lost the Sherlock part over a biscuit...'

Benedict Cumberbatch talks to Siobhan Synnot about Victorian detectives, Star Trek, big lizards and how he owes it all to afternoon tea
It’s close to midnight, and in a north London house two children snooze peacefully in bed surrounded by their Christmas booty, unaware that heinous deeds are being plotted in their kitchen. Every so often, one of the conspirators cocks an ear, then pads off at warp speed to check the kids are still out for the count, before resuming their part in evil doing.

Of all the items for inclusion as a DVD extra on Star Trek Into Darkness, Benedict Cumberbatch’s audition sounds the most intriguing. When producer-director JJ Abrams asked him to tape two scenes to test his suitability as the villain who brings chaos to the USS Enterprise in his science-fiction sequel, Cumberbatch cleared his schedule. Then, when he was unable to find a camera crew in London available during the Christmas holidays, he cleared space on his phone and hit ‘record’ instead.

‘People were knocking on my door, saying that while this was a holiday in the UK, LA was still working, and I had to send a tape now,’ he recalls. Eventually his best friend, actor Adam Ackland, offered his kitchen as a makeshift studio. ‘By the time I arrived, they had put my godson and his sister to bed, so I squatted under the one good overhead light, with Adam’s wife Alice balanced on two chairs holding my phone, and Adam feeding the lines to me.

‘Really they had enough on their plate without this strung-out actor in their kitchen, but we eventually shot three takes of each scene. Then it took me a day to work out how to compress the file and email it to JJ.’

Surely Abrams was so impressed by this technological resourcefulness that he gave him the job straight away? Cumberbatch laughs ruefully. ‘No, because it turned out he was on holiday. I was furious.’ But on 2 January an email dropped from Abrams – ‘Do you want to come and play?’

This is not the first time Cumberbatch has won a major role after co-starring with teapots and pans. He auditioned for Sherlock Holmes at the producer’s flat over tea and biscuits. ‘I thought I’d made a mistake taking the biscuit because that wasn’t a very Holmes thing to do. I thought I might have lost the part because of that.’

Show runner and writer Steven Moffat was looking to reboot Holmes into modern London while retaining the spirit of Conan Doyle’s show-off sleuth with brains to spare. Blackmail notes no longer arrive in the post but on a smartphone, and Dr Watson writes up Holmes’s casework on a blog, but the series still roughly adhered to the cornerstones of traditional Holmes – including the big lethal confrontation between the hero and Moriarty at the end of series two.

The show is also 36-year-old Cumberbatch’s first exercise in protracted secrecy; he refuses to offer any clues about how Holmes could survive jumping off a tall building. All we know is that there’s a third series, currently shooting, and Cumberbatch is back as Holmes. Three days after Abrams’s email, I met Cumberbatch to talk about his role in War Horse. His recruitment to Star Trek was all over the internet, with Trekkies analysing the choice and its implications with Vulcanesque thoroughness. ‘Go on,’ I say, ‘there are only two of us in the room. What sort of superpowered bad guy are you?’ Cumberbatch throws me a wry look. ‘I can’t say anything. Sorry to go cold on you, but there are lawyers in the cupboards right here with us.’

Keeping schtum must be one of the hardest aspects of Cumberbatch’s recent rapid rise to the A-list. Three years earlier, he could be raffishly indiscreet. He had just been horse riding, and needed no prompting to reveal that these cramming equestrian skills were for a new movie with Steven Spielberg. A born storyteller, he chatted easily in long, fluent paragraphs about auditioning for Madonna, who struggled to work her handheld camera, or a blithe account of filming Sherlock on a set adjacent to Matt Smith and the Doctor Who complex in Cardiff (‘Hello, Doctor.’ ‘Hi, Sherlock.’). He also gave me his phone number, in case I needed more quotes. I’m sure it’s been changed now.

Cumberbatch has become such hot property that he is in almost everything at the moment. He sports a bleach-blond look as Wikileaks founder Julian Assange in a movie called The Fifth Estate, studied lizards at London Zoo to provide the voice and CGI moves for the dragon Smaug in The Hobbit, and has agreed to step into Leonardo DiCaprio’s shoes for The Imitation Game, a film about the brilliant British mathematician Alan Turing.

This kind of workload would have Sherlock Holmes slapping on the nicotine patches and playing soothing music, but Cumberbatch, who came to acting slightly later than friends such as James McAvoy, is now determined to make the most of this new attention.

Along the way he has acquired a fanbase, the Cumberbitches, although he frets that the term is pejorative: ‘Cumberbabes’ is his preferred alternative. There are discussion forums, internet shrines and fan fiction, which tends to home in on Holmes. Something about the scene in Buckingham Palace, where Holmes is naked except for a sheet, seems to have established the world’s greatest detective as a lustbucket. ‘There’s some really weird crossbreeding stuff,’ notes Cumberbatch of the storytelling. ‘When I was playing Smaug in The Hobbit, suddenly there were lots of dragons with purple scarves flying around.’
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Cumberbatch has also been flying around, dotting between the UK, the US and New Zealand. Since his 12-year relationship with actor Olivia Poulet ended, there has been no serious girlfriend based in any of these places. Three years ago he had remarked rather wistfully that he would like to be a father by 40, but dating in public is a challenge. When he attended the Golden Globes for Sherlock, he took his PA Emily as his guest. When the paparazzi saw Cumberbatch getting into a car with her after the ceremony, they assumed this was a new chapter in his romantic history. ‘The flashes went off to the point that I couldn’t actually see. Poor girl, she’s never experienced that before. I’d never experienced that before. They were hanging off the bonnet of the car.’ The punchline? Emily is also his niece.

Perhaps because he spent a long time doing small roles in big films before the big bang of Sherlock, Cumberbatch is determined not to get carried away by the new heat he’s packing. ‘I am very flattered, although I don’t take it too seriously,’ he says. ‘I mean, I still have all the same weird things about me.’

The other thing that keeps him grounded is seeing the ups and downs of acting first hand. An only child, his mother is Wanda Ventham, a comedy actress who played Cassandra’s mum in Only Fools And Horses and Lesley Ash’s mother in Men Behaving Badly. Her son has inherited her wide cheekbones. His 6ft height is from his father, actor Timothy Carlton. Neither of them wanted him to follow in their footsteps, and hoped an expensive public-school education might set him on a different path. ‘They kept pointing out how uncertain their lifestyle was, and for a while I thought I might be a lawyer – after watching Rumpole Of The Bailey.’

How far did he pursue this? ‘I got to the stage of looking at degrees at Oxbridge, but a lot of people told me that barristers never knew where their next job was coming from… It sounded a bit like acting, so I stuck with that instead.’

From the age of eight, he was a boarder at Brambletye School in West Sussex. But if his parents had hoped to keep his mind off acting, they were rather scuppered by Harrow, where he landed his first stage role as Titania in A Midsummer Night’s Dream.

The breakthrough came when he played a grudging Salieri in a university production of Amadeus. ‘Afterwards we were in the car park and my dad said, “You are better than I was or ever will be” – which wasn’t true because he’s a great actor – “and you will have a really good time doing this for a living.” Which was a huge thing for him to say, and an emotional turning point for me, and I cried. Having got his blessing, I wanted to make him proud.’

Both parents stayed with him during Star Trek’s lengthy shoot. On set, he formed a small British clique with co-stars Simon Pegg and Alice Eve, watching British TV relayed on a Slingbox and drinking tea.

Cumberbatch, it turns out, is less science-fiction nerd, more a real science nerd. Earlier this spring, he was guest director of the Cambridge Science Festival. He also has a keen interest in astronomy, and counts Stephen Hawking as a friend since Cumberbatch played the astrophysicist as a young man in a 2004 TV movie. ‘He told me, “You’re better looking than me; I was more scruffy than you,” which isn’t true because I’ve seen the photographs. But he has got a good sense of humour. It can take a while for a oneliner to come out, but when it does, it’s fantastic.’

Consequently, Cumberbatch’s biggest thrill on Star Trek wasn’t boarding the Enterprise or trying on a Starfleet costume, but the filming on location at the National Ignition Facility in San Francisco. In the film, it doubles as Starfleet Academy, but its day job is housing the world’s largest laser. ‘It’s where Edward Moses is trying to create hydrogen fusion by using lasers fired at extraordinary speeds through various lenses,’ says Cumberbatch, sounding as gleeful as a ship’s engineer who has found a hidden cache of dilithium crystals.

‘If they can hit this target of hydrogen – which is half the breadth of a human hair in this huge cell – they will create this alternate energy supply, which could power San Francisco for a year with one burst.

‘So when we arrived in our costumes, with our cameras and dollies and lights, there was this huge tradeoff between scientists and film people, where we had the amazing privilege of being there, while they loved this crazy circus coming to town.’

Star Trek is on general release now.