BBC One has unveiled a teaser image for the 2015 Sherlock special that not only suggests the return of John Watson's facial hair, but also the possibility of period costumes. Seriously, those are Victorian or Edwardian clothes, right?

It was confirmed in July that stars Benedict Cumberbatch and Martin Freeman will be back at Baker Street next year with a 90-minute Christmas special, followed by a three-episode Season 4.

C0-creator Mark Gatiss, who also plays Mycroft Holmes, teased just last week that audiences can expect "tragedy as well as adventure" when the series returns.