"Sherlock" star Benedict Cumberbatch initially had qualms when co-creators Steven Moffat and Mark Gatiss first suggested that they wanted to take the Christmas special this year to 19th century London.

Cumberbatch told Wales Online that he "thought it was madness" to bring Sherlock Holmes and his faithful sidekick and friend Dr. John Watson (Martin Freeman) back to the past, but once they started filming it, the episode finally made sense to him.

"I thought they'd finally lost the plot, jumped the shark, and all the other cliches of television gone mad with itself. Then they expanded the idea and pitched it to me properly and now I think it's fantastic; absolutely brilliant," the 39-year-old actor said.

The episode, which is entitled "The Abominable Bride" is set in 1895 and will showcase steam trains, hansom cabs, and frock coats. Cumberbatch loves the setting and he hopes fans will appreciate the beauty of the set too.

"I think that's one of the joys of doing 'Sherlock' like this," he said. "We can't disguise the fact that we're filming it as we're often in cities or public places where people can take snapshots of us dressed in Victorian kit. We haven't disappointed fans in the past it seems, so hopefully this won't."

Freeman feels the same way. "I hope they like it. That's all I can say. That's all I think about everything I've ever done," he added.

The 44-year-old "The Hobbit" star also acknowledged the fact that they only have three episodes per season plus a Christmas special, but he reasoned that it is only because they take careful care in making each episode special.

"It changes the dynamic of filming because everything does take longer: it takes longer to get dressed, you're longer in make-up, you're longer in wardrobe and camera resets take longer just because there's more stuff about," he explained. "The clothes that we're wearing and the stuff we are dealing with as far as make-up and hair is concerned, are not everyday things that people have to deal with."

He added that the episode is slightly more formal than the previous ones, but they were conscious "not to completely change the characters people have come to know and love".

"I'm still recognisably John and Ben's still recognisably Sherlock," he said. "To muck around with a pipe and a deerstalker for real is wonderful. And then, as far as the background goes, the setting, the mise-en-scene, the scenery, all the rest of it, it's just a delight. It always is with period drama; you kind of marvel at it."