It is a capital mistake to theorise before one has data.Sherlock Holmes in 'A Study in Scarlet' and 'A Scandal in Bohemia'


A Sherlockian-style adventure of looking for clues, making deductions, and investigating mysteries that would make even the greatest consulting detective’s head spin. But what precisely is it, who takes part, and why?


“I am glad of all details,” remarked my friend, “whether they seem to you to be relevant or not.”Sherlock Holmes in 'The Adventure of the Copper Beaches'

In a nutshell, setlock is about following the filming of Sherlock. The tag #setlock was originally coined by Ruther2 on Twitter and used both to protect viewers from being spoiled and to offer a universal term for fans to use in following updates on the show. In some media, setlock is viewed as consisting simply of fans who show up to filming locations to follow what is being filmed that day, but in fact for many the process of “setlocking” and being a “setlocker” can be much more complex.

While perhaps the most obvious way of engaging with setlock is to attend a day of filming, this is difficult for the majority of fans, and is by no means the only way of collecting information about upcoming episodes. Those who do attend seek out locations through filming notices, crew tweets, or social media posts from members of the general public who happen across the film crew. Dozens, and at times hundreds, of people travel from near and far to stand behind pedestrian barriers and watch the filming of mostly exterior scenes, with possibly the best-known and most well-attended location being North Gower Street, the stand-in for Baker Street.

Some are just happy to watch, but others might take photos or document the process of the show being made and then share the images with thousands of fans via social media platforms. To take setlocking a step further, many tweeters and bloggers also scour the internet in search of any information that seems to be associated with the show, in addition to highlighting casual reports from the general public. It might be possible to work out in advance what to expect, or where to watch the next scenes being filmed. Setlock information can take the form of set photos, casting news, tweets and images from cast and crew or the management of potential venues, parallels to canon stories from Arthur Conan Doyle, and much more. But information-gathering is just the tip of the iceberg for a portion of the Sherlock fandom, who then start categorizing their findings in order to speculate further. For example, production designer Arwel Wyn Jones might tweet a photo from inside a room at a location recce, inspiring fans to deduce where the location might be and what kind of situation might lead the characters there.

So setlock exists on several layers, from the surface layer of watching the filming process to sharing experiences and newly-gained information via social media, to perhaps the greatest game of all: puzzle-solving.

"The Abominable Bride" | photo by Copper_Beech221

“The Abominable Bride” | photo by Copper_Beech221

The Setlock Phenomenon

To let the brain work without sufficient material is like racing an engine. It racks itself to pieces.Sherlock Holmes in 'The Adventure of the Devil's Foot'

There are various reasons why setlock has become such an event. Many fans attend the filming of Sherlock purely to see the process in motion, or perhaps to get a glimpse of the amazing cast or creative team. There’s a chance to see the incredible process of creating television from the ground up, the opportunity to get a photograph or an autograph from a favourite actor, or just the thrill of being smack dab in the Sherlock world along with other fans. It’s the sharing of passions, of experiences, of knowledge. It’s seeing the onscreen magic in the flesh, breathing it in, feeling every quiver of its beating heart.

But for others, being on the ground and at a location isn’t necessary, or is really only the very beginning. There are often long hiatuses between each series of the show, with two years between Series 2 and 3, and two more between Series 3 and the latest special episode The Abominable Bride. In this way, following the filming of the show provides fans with more content. For example, the filming of Series 4 is predicted to run from April to July/August 2016, thus supplying an entire four or five months of additional material for fans to engage with. For fans who deal with years of hiatuses, this can feel like being a kid in a candy shop, offering more opportunities to connect with characters, locations and an overall storyline they may have been following since 2010. When a show has only has ten episodes, some fans will take anything they can get just to maintain a sense of connection.

Setlock also enables fans to engage with cast or crew from the show. As mentioned above, production designer Arwel Wyn Jones often tweets photos from pre-production, and sometimes writer/producer Mark Gatiss will tweet a few words or photos to pique interest. Douglas MacKinnon, director of The Abominable Bride, is also a regular contributor of clues, sometimes tweeting photos from locations and other times supplying images of things that may have inspired him while filming. Fans often engage Jones, online or at conventions, about his colour or wallpaper choices; likewise Claire Pritchard (Hair and Makeup) gets attention for her hair and wig techniques. Fans have been able to follow photos tweeted from backstage of music being recorded, photos of scripts during read-throughs, and computer screens during the editing process. Following setlock gives fans the chance to engage with the show during all phases of the process, whether that be pre- or post-production, allowing for a fuller understanding of all the hard work that goes into making the show, who is involved in the process, and how all the cogs in the machine work together.

"The Abominable Bride" | photo by Copper_Beech221

“The Abominable Bride” | photo by Copper_Beech221

For other fans, there’s even more complexity to the reasons setlock is such an important aspect of their fandom experience. Setlockers can step into the shoes of Holmes himself, or perhaps one of his Irregulars, gathering clues to solve a great puzzle. Piecing out possible plot structures or engaging in other types of speculation from clues found on set or in social media lets fans engage their own minds as well as to interact with fellow setlockers, working together to make sense of nebulous pieces of information gained over weeks, or sometimes even months or years.

The beginnings of a Setlocker

Nothing clears up a case so much as stating it to another person.Silver Blaze

I found myself navigating around Sherlock-themed social media on day one of filming for The Abominable Bride, and immediately graduated to immersion in the information the Sherlock fandom was gathering online.

With a background in theater and live event production, I was immediately interested to see how the show was being made, and so started to follow people who were attempting to document the process on both Twitter and tumblr. I researched photos and watched the DVDs from the making of past episodes to give me an idea of what to expect, and also to compare and contrast what actually made it into past episodes versus what got cut.

My initial involvement in setlock was simply blogging about what others were saying or discovering, but as the days went by I began to engage with the content being researched or speculated about. If the cast, crew or fans took a picture I would try to ascertain what it was or what it meant, or how it might feature in the story. I began to reflect on the content with others, trying to see what characters, scenes, sets, costumes, and props we’d identified and how they might fit together to create a narrative.

A few weeks into the process, fans learned that filming was finally going to take place on North Gower Street. Despite the cold weather and the possibility of crowds, I decided to take advantage of my proximity to the location to try to attend the filming and get into the heart of the process.

Setlock, in the flesh

There is nothing like first-hand evidence.Sherlock Holmes in 'A Study in Scarlet'

On a cold February morning I donned my winter coat and took the Tube to Euston station, which is close to North Gower Street. Filming for the Sherlock special promised to be different from its predecessors, for while past episodes were focused on adapting Arthur Conan Doyle’s stories to the modern world, The Abominable Bride was going to be a special episode set mainly in 1895. There was already a small crowd forming behind the pedestrian barriers, and I slotted myself into the mix to watch as crews set up for the day, assembling everything from large green screens to tracks to cameras. Victorian props arrived, along with vehicles including horse-drawn carriages, as well as a slew of supporting actors for a large crowd scene.

Setlock is not the most glamourous of ‘events’. For the filming of The Abominable Bride the cast, crew and crowds alike all had to endure cold temperatures and hours of filming for only a few scenes. From the viewpoint of someone not working on set, it can look like a slightly tedious process, and certainly a complicated one. Hours of watching filming is not for the faint of heart, especially when fans must stand for the entire time amid a sea of dozens, or at times over a hundred, others. But many stick with it, some for the opportunity to get a glimpse of the actors or the creators, and others, like me, simply to try to get as many clues as possible as to what is happening during the filming and how that fits into the overall storyline of the upcoming episode.

Perhaps because of my interest in production, the hours flew by, and I kept myself busy tweeting what was happening to those who could not come down to the filming location, often answering questions from bloggers around the world. Well, to be perfectly honest, that and running to the nearest cafe to grab a cuppa, thaw out a bit and recharge my phone battery! But as soon as my fingers started working again and North Gower Street called to my heart, I was back in the throng of fans, standing on tiptoes or peering around elbows to catch a glimpse of camera positions, running crew, props… anything I could take in.

A clapper loader holding a slate | "The Abominable Bride" | photo by Copper_Beech221

A clapper loader holding a slate | “The Abominable Bride” | photo by Copper_Beech221

It was also a chance to meet other fans, including some who had traveled from around the globe just for a chance to see the show being made. The environment can be a bit daunting, with quite a big crowd at the more popular and well-known locations like North Gower Street, but on the day in question crowds were well-behaved despite the number of people and the conditions. A relationship grew between the security staff and the setlockers, as quiet was often necessary and sometimes onlookers needed to be moved if shots had to change perspective.

After a long day of filming I returned home to put all my thoughts together, trying to pass on information and clues that I’d seen to others who’d been talking to setlockers from various positions on-location, thus getting a broader perspective on what different moves or variations of a scene had been filmed. Anything and everything was documented, and theories had sprung up just minutes into the day. I’d attended in person, but I still had to catch up on what everyone else had seen and learned!

Luckily for me, I got to do it all over again the next day. This time we were in a different location, just off Pall Mall, and it was a bit of a shorter day, but still as fun and informative. I can’t begin to explain the amount of things I learned about the show and, more broadly, the process of television-making, from how the special effects team worked on distributing snow to how the supporting actors were moved around on-site. Attending such an ‘event’ really allowed me to see how much work and how many people it takes to pull off a show like Sherlock, and the stamina needed by every single crew and cast member.

Setlock not only deepened my connection to the process of making the show, but also allowed me to engage and communicate with other fans, sharing our passion and also working out different pieces of the puzzle before pooling our findings. On an even more personal level, attending the filming of the show really inspired me in my own career aspirations in media production. Holmes himself might scoff at the sentiment, but just two days of watching the filming process was truly magical and life-changing for someone who has always been passionate about creating and sharing stories, and about the different ways these stories can be made. Watching Sherlock being filmed, and learning about many of the different elements and participants, from creatives to production, has made me hungry to keep learning.

An ending hiatus

It is of the highest importance in the art of detection to be able to recognize, out of a number of facts, which are incidental and which vital.Sherlock Holmes in 'The Reigate Puzzle'

Only one episode was filmed in early 2015, leaving fans with almost a year to deduce how the crew might put all the fragments we’d learned at setlock together to make the upcoming episode. The amount of sleuthing that went on for just a 90-minute episode, albeit one set in a Victorian world so different from our own, was astronomical. Fans pored together over different findings and clues, each providing different skills and viewpoints to further the discussion. Some with a background in music theorized on what we might hear, others researched the Victorian era to see what elements of history, scenery or props could be used with what we already had seen on set, and others catalogued the differences seen in costumes and what this might tell us about the time period the episode was set in or the number of days it covered.

Fans versed in cinematography were able to teach others about different cameras, and how the use of one model or another might affect the look of scenes. Others documented how clues from different filming locations fitted together to create a single day within the episode.

Still others put together clues from past cast and crew interviews to see what light they might throw on setlock findings, or speculated on how past Arthur Conan Doyle stories might be referenced through different props, costumes or sets.

By the time The Abominable Bride aired in January 2016, much of the content had already been discussed, but there was still plenty of material that setlockers had not shared with the rest of fandom, and no matter how much sleuthing had been done there were still surprises along the way. It was invigorating to first see the hard work fandom put into its deductions, and then to witness some of the theories borne out on screen, and especially to watch the mysteries we were never able to solve, no matter what clues we found, finally being explained before our very eyes.


Let us hear the suspicions. I will look after the proofs.Sherlock Holmes in 'The Adventure of the Three Students

Despite the positive aspects of setlock for many fans, it does not come without its own controversy. In the past, this has even been covered and commented on in the media, especially with the growing popularity of the show. There have been issues with crowds who have been too loud or intrusive to filming, which has led to comments from some cast and crew about the difficulties resulting from the presence of fans on location.

Equally, though, there has been support for the fans from other cast and crew members, who have made positive comments about the passion and respect shown by many visitors. Right before the filming of The Abominable Bride there was a blast of negative publicity about fans on set, arising from experiences during the filming of the third series. But these articles and fan reaction to them were soon followed by producer Sue Vertue telling fans that certain comments had been taken out of context, and fans were still allowed to visit the filming. Vertue’s most recent comment was specifically about the first day of the North Gower Street filming that I attended, and I there observed that fans made less noise than I had assumed they would from reports in mainstream media, and quietened down and moved when asked. Things weren’t perfect – due to the large crowds, space was sometimes an issue – but all in all it was a relatively peaceful experience. Later, on social media, the crew thanked fans for their respectful behaviour, and actors such as Una Stubbs and Loo Brealey have gone on to make similar comments.

When the cast and crew started tweeting about the filming of each previous series, they probably didn’t expect the growth of the setlock phenomenon and the resulting level of engagement. However, while fan attendance at filming may have been underestimated in its scope and ramifications, after a few years fans and crew have created a respectful dialogue.

The Future of Setlock

What one man can invent another can discover.Sherlock Holmes in 'The Adventure of the Dancing Men'

With the ever-increasing popularity of Sherlock, fans’ physical attendance at filming locations is likely to increase as well. Pair this with the warmer weather likely during the Series 4 spring and summer filming – as opposed to the winter filming of The Abominable Bride – and North Gower Street, for example, will most likely draw hundreds of people, all playing the setlock game at different levels. This will bring familiar controversies over fears of filming disruptions and spoiler leaks, although those are as likely to come from the paparazzi as from fans. Hopefully the established relationship between fans and crew will lead to a respectful and productive environment. There are already communications being distributed to fans who might attend filming, covering subjects from appropriate dress for cold weather to suitable behaviour while the cameras are rolling.

The crew are also engaging with fans and social media during the upcoming series’s pre-production. Jones, for example, has tweeted images of his crew setting up props and studio structures as well as site recces for possible filming locations. This has already led to fandom deductions about sites where we might see the crew in the future, with a photo of a prop leading one fan to identify the statue referenced, and another fan to identify its location. Other fans have used a photo of the inside of a cathedral to identify the building and look up the shows that have already used it as a location.

To play the setlock game one need not travel to London or other filming locations, but merely engage respectfully with the cast, crew and other fans who are already talking on Twitter and tumblr about the upcoming series. #setlock is followed by most dedicated fans, whether they’re blacklisting it to avoid spoilers or using it to track what the crew is up to and what speculations fans are making based on the clues so far. One of the greatest things about setlock is that fans both old and new can engage with the upcoming series, and it’s always about thinking and learning, from the show and from other fans.

This is just one of the many games the Sherlock fandom plays to engage with the content offered by the show, and it’s really not all that different from the game played by readers of Doyle’s original stories over a century ago. A game of being introduced to settings, locations and characters. and wondering how all the puzzle pieces slot together, what the mystery is, its context, how all of the clues fit, and how it might all play out in the end. We are Baker Street Irregulars of a sort, blogging, deducing, and eliminating the impossible until what remains, however improbable, must be the truth.

On April 4, 2016 production for Episode 1 of Series 4 of Sherlock officially started, with most location and studio shooting taking place in Cardiff, Wales. A short video from Mark Gatiss was released, showing an empty slate, fog, and the vaults of a location at Portland House. There’s an aura of mystery and excitement as he proclaims, “The Game is On!”

Mark Gatiss with a blank slate for Series Four, Episode One

Mark Gatiss with a blank slate for Series Four, Episode One


Several weeks into the process of filming Series Four and there are both new and old players of the setlock game working together to deduce clues, sometimes from the most ambiguous pieces of information. The crew continue to play along, tweeting tiny parts of props or locations to tantalize fans, or sometimes even sharing detailed shots of well-loved props, and especially of the interior of the 221b studio set.

Setlockers have identified one filming location using only a few background elements from photos and a crew video of a rainbow, using Google maps and a previous episode of Doctor Who to pinpoint sites. Others are examining documentation of stones from the 1600s at a church abbey to help analyze a photo of a date etched in sandstone sent by Jones during filming. Plots are being speculated upon, information debunked, and ideas shared.

These are just a few examples of how setlock is heating up at the time of writing, even though few actual production photos have so far been released by crew or seen by fans or paparazzi. Regardless, the fandom will continue to play the game with whatever pieces are available, working together to share the love of the setlock process and the plethora of mysteries awaiting.