Benedict Cumberbatch and Martin Freeman will be heading back in time for a Sherlock special set in Victorian London, creator Steven Moffat has confirmed.

The one-off show will be “its own thing” and stand alone from the upcoming fourth series, due to air in early 2016.

“We wouldn’t have done the story we’re doing, and the way we’re doing it, if we didn’t have this special,” Moffat told Entertainment Weekly at SXSW Festival.

“It’s not part of the run of three episodes. So we had this to do it – as we could hardly conceal – it’s Victorian. [Co-creator] Mark Gatiss and me, we wanted to do this, but it had to be a special, it had to be a separate entity. It’s kind of in its own little bubble.”

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Many fans will be unsurprised by this news after the BBC released a first look picture of Sherlock’s lead stars in Victorian get-up last year, prompting speculation over whether time travel was involved or they were simply dressing up for fun.

Since then, photos have emerged from the set showing the cast in 19th century clothing.