Sherlock: The Abominable Bride is the must-see New Year’s Day highlight.
Holmes and Watson, played by Benedict Cumberbatch and Martin Freeman, are transported back to 1895 for the one-off special.
And Steven, 54, says there was an appeal in seeing the pair back in the original times that the Conan Doyle books were set.
“It was irresistible to do a special that is Victorian and say, this is what it would’ve been had we done it authentically,” said Steven.
“There was the CGI needed to recreate a Victorian London that you believe in. In terms of the writing, we wanted to keep faith with our version of those characters, and yet put them in a Doyle setting.
“The modern-day Holmes talks very much like the Victorian Holmes.
“In fact, if you look at the modern version of the show, he sounds more and more Victorian every year because Benedict suits that.”
Steven says the original characters and stories are so good they’ve helped keep it a monster hit for over a century.
He concedes, though, that it is a “very different” episode.
But if viewers are a bit unsure about the idea of the crime- fighting duo being transported back 120 years, it was nothing to his leading man’s reaction.
“I thought it was madness,” admits Benedict.
“I thought they’d finally lost the plot, jumped the shark, all the other clichés of television gone mad with itself.
“Then they expanded the idea and pitched it to me properly and I think it’s fantastic. Absolutely brilliant.
“To muck around with a pipe and a deerstalker for real is wonderful. And then, as far as the background goes, the setting, the scenery, all the rest of it, it’s just a delight.
“It always is with period drama. You kind of marvel at it.”
And having made the show a global hit and one that fans relish, he’s hoping that it doesn’t disappoint.
“I don’t really know how the fans are going to react to it,” he adds.
“I think that’s one of the joys of doing it like this.
“You know, we can’t disguise the fact that we’re filming it and often filming it in cities or public places where people are going to take snapshots of us dressed in Victorian kit.
“We haven’t disappointed fans in the past it seems so hopefully this won’t.
“I hope they enjoy it.”
Sherlock New Year’s Day, 9pm, BBC1
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