Cumberbatch expressed how excited he is to finally portraying a Victorian Era-Sherlock. The actor said that he could finally stretch out the emphasis on the brilliance of his character who he said is out of his own time.

Cumberbatch told Telegraph, "To put him back in the era that he's written in is a joy. Things I tried to impose a little on the modern version -- his physicality, his stature -- are done by the costumes: the collars, the deerstalkers and cape. It's a delight."

Cumberbatch also expressed his relief on dressing according to original era.

"I thought, at last I can have a f------ haircut. We could get rid of that ridiculous bouncy lot of curls on my head."

Cumberbatch's hair in the next episode will be slicked back, Victorian-gent-style, and he wears a stiff collar and dapper tweeds.

On the other hand, Martin Freeman, puts on a huge caterpillar-like false moustache for the Victorian episode.

"We're trying not to be too winky about it, and too self-knowing. Sometimes when things are set in, say, the Seventies, it's our way of laughing at people from the old days. I don't find that very interesting."

he added that instead, the setting "makes you amend what you're doing very slightly. The plan wasn't to suddenly present a whole different character, or a pastiche, but it does tighten you up physically and vocally."

Freeman also said that the relationship of Watson and Holmes will still be there in the era. The only difference will be Watson's longer patience with his best friend.

Mark Gatiss explains that the episode doesn't represent a "long-held dream," since it would mean that they have been forced to make all those modern-era episodes just to earn a Victorian one. It's not like that at all.

"We've joked about the idea for a long time, but it's just so massively appealing to do both. The only other people who've ever done it," Gatiss said. Basil Rathbone and Nigel Bruce were the only ones to play Sherlock in both a period and modern settings.

A lot of people believe that the fourth season of Sherlock may be the last one because of the success of Freeman and Cumberbatch. The season 4 alone had experienced a great amount of delay because busy schedules.

However, Freeman said the he believes that the show will continue as long as the people involved still wants to do it. Cumberbatch also said that he is still interested and grateful for the role.

"I don't know any other actor that's been so spoilt with this role," Cumberbatch said. "I've said many times I'd love to keep ageing with him."

Cumberbatch added that their duo started "fairly young" on their roles compare to the other actors who have played the role. "So why not?"

Sherlock season 4 is said to begin production next spring according to KPopStarz. Rumors say that there might be a spin-off series including Benedict Cumberbatch's Sherlock Holmes and Lara Pulver's Irene Adler.

"Sherlock" Christmas special airs on New Year's Day on BBC.