Sherlock: 360° video of London filming locations

What? BBC's Doctor Who once visited Sherlock's set! Believe it or not, we have a proof.

Director Rachel Talalay, who worked on both Sherlock and Doctor Who, recently took to Twitter to share a photo of Doctor Who star Peter Capaldi dressed as the Time Lord sitting comfortably in an armchair at 221B Baker Street.

Also read: Sherlock Season 5: Benedict Cumberbatch to return to small screen soon

Talalay posted the old photo on the social media platform on Monday morning. Check it here.

The 59-year-old director captioned the photo: "Promised #LIWho I'd finally post this: #PCap visiting (no conspiracy) me at #Sherlock221b last year. In costume as he was working on Class that day. Now i'm done over-explaining, great moment for. [sic]"

Capaldi had been filming for the Dr Who spin-off Class at the time.

Fans are going gaga over this picture. Some of them even made a few wild guesses, saying either the Doctor or the British sleuth is the client.

Benedict Cumberbatch-starrer Sherlock Season 5 might return to the small screen soon. But there are no official details about the series' further production.

Recently in an interaction with The Sun, Sherlock actress Una Stubbs, who plays Mrs Hudson in the BBC series, said: "We're waiting to hear if there will be more Sherlock. The boys [Cumberbatch and co-star Martin Freeman] are so busy. I'd be game for more. They'd have to hurry up, though – I've said that Mrs Hudson would need a Zimmer frame!"