Speaking to Sydney Morning Herald, Sherlock – The Abominable Bride writer Steven Moffat claims the Holmes character works regardless of time period:
What we were doing all the time was saying Sherlock Holmes does work, even though he’s got an iPhone. Basically the question was, how can Sherlock Holmes work in the world where he has an iPhone? Then, within seconds of the show going out, I mean seconds, by the time we were promoting episode two people had so gotten used to the idea that it was updated that it’s never really been raised again. It just disappeared and it became its own thing. Hopefully that meant that [co-writer Mark Gatiss] and I were right when we said the period setting isn’t that important. Of course … what’s the first question we get? No kidding, it was how can Sherlock Holmes survive without his iPhone? There is some precedent for that. Back into its original setting reveals all the things that we changed … you suddenly think, hang on, the women in the Sherlock Holmes stories basically don’t talk. Mrs Hudson doesn’t speak. We’ve got a bunch of characters who according to Doyle tradition shouldn’t speak at all, which is not what we’ve done. He’s ruder in the modern day because he doesn’t have Victorian manners. He doesn’t have any of that gentlemanliness. Sherlock Holmes in the original stories is quite believably a God-fearing man and a royalist, things that you could not imagine being true of the 21st-century version. Put him back in that world, and as you’ll see from Benedict’s different performance, he is a sort of suaver, gentler, still terrifying but suaver and gentler man and he’s a Victorian person. Those things are very, very different. I think for everybody involved in it, it is one of those delightful surprises that happened. We didn’t see it coming at all. We thought we were making a good show. We did think it was good. We weren’t modest about it in that sense. But we thought it would be fine. It became a sort of magical, huge hit. There’s a genuine moment in everybody’s life when that happens. That’s something special, and we’re all sentimental enough to want to keep going on with that. And because it’s good, it’s a nice thing, isn’t it, to come back, and this one’s good. Sherlock Holmes is more than a story, it’s a myth. That’s eternal. I mean, he’s been living there since 1880, what is it? So it’s not going to change. We’re not building to an end point or a thing that ends it all. We know how it ends. If you don’t know how to end you can check his books. Beekeeping on the Sussex, that’s how it ends. That day never comes, as Robin Hood is still in Sherwood and Sherlock Holmes is still on Baker Street. So it’s not like Breaking Bad or any of these things because you have one big story. Also, legitimately they’re allowed to end it. We can’t. Sherlock Holmes and Dr Watson will always be there. Always.