Over the last few days, posters, flyers and even graffiti have been popping up around London and the rest of the world – all baring slogans like “I Believe In Sherlock” or “Moriarty Was Real.” The campaign has garnered a large presence on Twitter, but are the posters clever viral marketing, or the work of passionate fans?

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Well, it would seem what we are witnessing is actually just a fan movement – albeit an extremely impressive display of fandom power. The posters have appeared all over the world, from the UK, Europe and America, to Brazil, Mexico and parts of Africa. Many of the pieces direct fans to the Twitter hash tag #believeinsherlock, which is proving to be very active as dedicated fans and bemused non-Sherlockians share pictures of the posters they come across.

It’s difficult to tell exactly where the craze originated from, but this Tumblr blog seems to be one of the first to join in.

Above is a selection of our favourite pictures, taken from the Believe In Sherlock tumblr as well as the twitter hash tag. If you would like to share any pictures of the movement, either made by yourself or ones you have found in the street, share them in the comments or email them to harri@hypable.com and they will be added to the gallery. Also, be sure to let us hear your thoughts on the posters in the comments below!