Sherlock series four begins filming and fans are preparing for #Setlock

Sound the Sherlock alarm. Series four has officially begun filming, and that means one thing: #setlock is back.

In case you're not on the case, #Setlock is the phenomenon where hundreds of fans of the BBC1 show gather to watch filming, post pictures and share the joy of watching their heroes in action.

Amanda Abbington announced the news that filming for Sherlock series four had begun with these simple words.

Sherlock hair and make-up designer Claire Pritchard clearly had a busy day ahead, and had taken appropriate precautions.

#Setlock has been controversial amongst Sherlock fans in recent years, with some worrying that their presence hinders filming, and others afraid of potential spoilers.

Thankfully, Sherlock fans are a pretty careful bunch, and aren't about to go out of their way to spoil anybody's fun.

That's not to say people aren't still excited.

Really excited.

Will you be following #Setlock online this year? Or do you prefer to wait until the series starts? Tweet, Facebook and message us below with your thoughts.