Sherlock creator reveals "best episode" in show's history – and why 15 years is not a proper anniversary

"I'll stop you, because 15 is not an anniversary," he said. "I'm prepared to talk to you in five years' time, but 15… you see this persistently online. It's like, ‘Oh, it’s a year ago today’, and you're going, ‘Let it go!’ Or, ‘It's the 17th anniversary’. It's not a real thing.

"Of course, I'll talk to you about it, but there's no point in an artificial anniversary. There are certain benchmarks, like 20 and 50, but I'm not sure 15 is one."

In spite of this, Gatiss, who not only co-created the series but also played Mycroft Holmes, went on to speak about the show in depth – how it always came back to Conan Doyle's works and which of the 13 episodes he thinks is "the best".

"The whole point of it was, we used to call it a restoration," he explained. "We were asked to do novelisations, and we said, ‘Absolutely not. Go read Conan Doyle!’ And I remember lots of people who thought we'd been terribly clever by having Dr Watson in Afghanistan, and then I remember someone said, 'But I've just read it, that's Conan Doyle!’ Yes, that's the point.

"So, wherever possible, we tried to do it as a sort of version. The best episode, which is definitely A Scandal in Belgravia, which is fantastic, I think is a sort of an explosion of that little story, and yet it has all the beats. You know, Sherlock still disguises himself as a clergyman, he has to create an emergency in the house, Irene Adler beats him - literally - things like that."

A Scandal in Belgravia, written by Moffat, was the first episode of the show's second season. It saw Benedict Cumberbatch's Holmes meeting Lara Pulver's Irene Adler, a dominatrix who had become a target of various factions because she was in possession of compromising photos of a member of the royal family.

"We’d always go back to Doyle," Gatiss continued. "Funnily enough, one of my absolute favourite stories is a tiny story called A Case of Identity, which only really works on the page, but it's got little bits in it. And I think I maybe mined that like four times. I went back and found, ‘Oh, that's a beautiful little exchange.’

"Or Holmes is watching the client, and they're havering on the street, so he knows they can't decide whether to come or not. And then they pull rapidly on the bell pull, and he says something like, ‘A rapid bell pull always means an affair of the heart’. It's so gorgeous.

"And there were little bits like that that were constantly available to us, because he was a genius. Doyle was a genius, and he'd been there before."

Read more:

• Doctor Who's Mark Gatiss reveals how Jon Pertwee helped shape his Bookish detective
• Bookish season 2 confirms Bridgerton star and more returning cast for new episodes

During the conversation for The Radio Times Writers' Room, Gatiss also spoke about his work on The League of Gentlemen, Doctor Who and his new detective show Bookish.

In that series, Gatiss plays Gabriel Book, the owner of an antiquarian bookshop in 1946 who also helps the police solve crimes.

Mark Gatiss's interview for The Radio Times Writers' Room is available on RadioTimes.com here and on YouTube here.

Sherlock is available to stream on BBC iPlayer. Bookish will air on U&Alibi from Wednesday 16th July 2025.

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