The 39-year-old actor plays the titular role in the hit television series, which is a modernised adaptation of stories featuring legendary detective character Sherlock Holmes.

Sherlock Holmes was originated by writer Sir Arthur Conan Doyle near the close of the 19th century and although Benedict's TV show is set in present times, producers decided to return to 1895 for the forthcoming special, which is entitled The Abominable Bride.

“In fact, I went, ‘You’re mad’,” Benedict told The Independent about his reaction when he learned producers were travelling back in time for the episode. “I genuinely didn’t understand how they were going to get away with it."

Benedict became more convinced after reading the script for The Abominable Bride and then he started to realise depicting Sherlock Holmes in modern day is far more awkward.

“And then I got the more detailed pitch and I thought, ‘OK, this is going to be great fun’, And it really is," he smiled. "It’s so nice to play him in his era. The things that are asked of me in the modern version, the sense that this is a man clearly slightly out of his time... to put him back in the era he was written in originally is just a joy. It feels easier.

“And then there are things I tried to impose on the modern version, like his stature and physicality – a lot of that’s done in the Victorian version by the clothing, the collars, the deerstalker and cape and pipe and things.”

Actor Martin Freeman plays Sherlock Holmes' classic sidekick Dr. John Watson in the television series and like his co-star Benedict, he was initially concerned about returning to the Victorian era for the standalone episode.

“But then I was originally resistant to Sherlock because it was modern,” Martin reasoned. “Before I read the scripts (for series one) I thought ‘Hmmm, modern Sherlock Holmes could be rubbish. I’ve overheard (co-creators Mark Gatiss and Steven Moffat) say a couple of times while we’ve been on set that, ‘Finally we’re doing it properly, we’re doing the correct version at last’. It’s nice to ring some changes, I guess.”

The Abominable Bride episode of Sherlock broadcasts in the UK on BBC1 and in select theatres worldwide on 1 January 2016.