British actor Benedict Cumberbatch bristles when it is suggested that his new movie character Doctor Strange is "Sherlock, with magic".

Doctor Strange, the latest superhero from the Marvel Universe to hit cinemas, at first glance looks to be brainy and arrogant - traits apparently shared with other Cumberbatch characters Sherlock Holmes (from the highly popular BBC series Sherlock), the mathematician Alan Turing (The Imitation Game, 2014) and the villainous Khan (Star Trek Into Darkness, 2013).

"No, he isn't 'Sherlock with magic'," says the English actor, 40, at a recent press event in Hong Kong to promote Marvel's Doctor Strange, which opens in cinemas tomorrow.

In rapid-fire mode, he ticks off the traits that make the Marvel master of the mystic arts different from the emotionally isolated detective he plays on television.

"He's not a sociopath. He lives in the real world. He has sexual appetites. He's not despised by his colleagues, he charms them, he's witty with them... I would never want to play Sherlock in another form," he says.

What's strange? Cumberbatch's second toe

The insinuation that his range is limited to playing a certain type seems to have touched a nerve. He goes on for a bit longer about how Turing is unlike Sherlock, before conceding one point.

"They're clever. That's the only little cross-section you've got between them. Any character can be arrogant in the moment, or have misguided confidence.

"I don't fear I'm treading in the same territory. There are endless differences," he concludes, ending the moment of awkwardness in the room.

Everyone exhales.

Was it so wrong to suggest that there might be an overlap in his roles? He has played dummies - see his Little Charles in August: Osage County (2013) - and he has done oddballs (the androgynous All, in Zoolander 2, 2016) and voiced a dragon (Smaug, in The Hobbit trilogy, 2012 to 2014).

But it was his long-running role in Sherlock that cemented his status as the plummy-voiced English heart-throb of the moment.

Neither the size of his cult-like fan following nor the fans' ardour has diminished despite his marriage last year to English theatre director Sophie Hunter and the birth of their son, Christopher, now one year old.

He claims to be puzzled by what his true believers see in him.

"This other group of reporters asked me what my 'strange' thing was. I told them my second toe is bigger than my first. I look in the mirror every morning and I go, 'Um'," he says, making a gesture of bewilderment.

"I have a nice tan because I've been on holiday so I look reasonably healthy, but I can't see what other people see."

Referring to the years spent playing small parts, he adds that "I started my career as an actor, not a pin-up".

"It was 10 years before anybody started going, 'Ah'," he says, mimicking the sigh of the lovelorn.

"It still makes me laugh. If it went to my head, I'd be in a lot of trouble. I'd never leave the house."

The movie's director, Scott Derrickson, 39, has had a taste of the passion the actor can ignite. They were shooting in Nepal, which the American helmer figured would be far away enough from the frenzy. He was wrong.

"It was like being with Elvis in America. It was crazy. There were thousands of screaming fans. The fandom is incredible and it's about to get a lot bigger," says Derrickson.

Bigger, because this is the first time the actor is the leading man in a major popcorn movie, and as a Marvel superhero to boot.

Derrickson had Cumberbatch in mind for the part when he was developing the screenplay (and Tilda Swinton for the part of the sage The Ancient One), he says.

The hard part was working out how to make the Doctor's multidimensional world work on screen.

The Doctor is a hot-shot neurosurgeon who suffers a crippling injury after a road accident. His path to healing takes him to Asia, where he learns sorcery and martial arts.

With his fellow mystics, he fights villains in alternate dimensions in which planes of travel shift and even time can be twisted.

Derrickson took inspiration from the avant-garde 1960s comic book art of Strange's creator Steve Ditko and sources such as surrealism.

"Visually, it's probably the darkest Marvel movie. During the mind trip scenes, there's some freaky stuff there," he says.

•Marvel's Doctor Strange opens in cinemas tomorrow.