Mark Gatiss posts first picture of Benedict Cumberbatch on Sherlock set – but is he wearing a wig?

Benedict Cumberbatch is #221Back again – and Mark Gatiss has the Sherlock series four set photo to prove it.

The first snap of the Sherlock star is typically enigmatic, showing only the back of Cumberbatch’s head. Sherlock is staring out of the window, jacket collar up, wisps of hair curling over his ears…

Back! #Sherlock pic.twitter.com/WFvpGpy3PV

— Mark Gatiss (@Markgatiss) April 11, 2016

And here’s where the mystery begins. Is it Cumberbatch’s real hair this time?

A bit of background: Cumberbatch wore a wig for the modern scenes in Christmas special The Abominable Bride, and now fans are worried they can’t tell whether Sherlock’s locks are real or not.

'ellooo. Window spoiler alert! What's the verdict, #SHERLOCK fandom? To wig or not to wig? #setlock #221Back

— ????????↔️???????? (@freewomenxgrape) April 11, 2016

Hair and make-up artist Claire Pritchard is enjoying the debate immensely – but isn’t giving away any clues.

@Markgatiss Thanks Mark! My Twitter feed going crazy with wig or no wig speculation! #twist&diffuse it's good to be back!!!! ????

— Claire Pritchard-Jones (@Claire_cpj) April 11, 2016

Meanwhile, other fans think there’s something a little Strange about Cumberbatch’s return.

.@Markgatiss There's something strange… pic.twitter.com/yHcNn4TSJX

— Olly Gibbs (@OllyGibbs) April 11, 2016

New Marvel movie Doctor Strange is set to be released in October, with Sherlock series four expected to return to BBC1 in January 2017.