So the trailer is out - and a very wicked tale it weaves. It starts with the trademark "I-Know-What-you-Did-'Coz-I'm-Sherlock" music and the pans over to Mrs Hudson doing the dishes as a Sherlockian shadow streaks across the door. Then there's LeStrade in a dark alley/parking lot reaching for something in his pocket as he whips around to catch sight of what memories shadows jog by. Pan to the high-and-mighty Mycroft reading, well, a newspaper who looks up in sartorial style as a Sherlock-like shadow dashes by; to finally the back of woman, presumably Molly Cooper - is it grey in her hair?

Finally, the coup de grace - the camera focuses on a slightly-older look Martin Freeman and lo, he has a moustache - eating his lonely dinner with a glass of wine at a restaurant ala bachelor. Focus on Sherlock who's looking a tad nervous and waiting for his friend to look up and notice and him and do something...

So while the trailer is great - the world is wondering about the real reason behind the moustache.

Is it a mark of respect for the dearly departed? Is it the demand of the mystery woman in his life - considering he's to be married in episode 2 of this much-awaited season? Is it a sign of him being a successful doctor or writer? Perhaps the blog has taken off into a biography of the man in question and has earned him a handsome pie... Or maybe it's just a psychedelic attempt to mould Watson into a spin-off from Doyle, the way Sherlock's deerstalker got woven into a humorous joke in the new Sherlock. So how will they explain the new tash of Watson? The writers will definitely give the fans a surprise twist.

Doyle's Watson had a moustache for a tame reason - from the late 19th century until 1916, British soldiers were forbidden to shave their upper lips. Si if you were in the army, you had a moustache. While Watson was discharged after he got wounded, but he may have kept the moustache because he liked it or that it reminded him of the days gone past!

Is this the same case with Martin's Watson? We'll have to wait till 2014 when the season3 of Sherlock premieres! Meanwhile, watch the video of the trailer of season 3.

Read More:

The better Watson and the better Sherlock. Plus Season 3 Episode List & Spoiler