Doctor Who thing of the day: does the TARDIS appear in Sherlock: “The Hounds of Baskerville”?

[NO spoilers for “Hounds” in this post!]

Life, Doctor Who & Combom notes that some viewers spotted what appears to be the TARDIS in the opening sequence of Sherlock: “The Hounds of Baskerville.” Here’s a high-def screengrab:

Click here for a much larger version, without the red arrow. Here’s a zoom in on the area from that large version:

On Twitter, Steven Moffat said:

Sue says that isn’t the TARDIS, it was a lighting thing. But by my cuff links, what ELSE could it be???

Sue is, I presume, Sherlock producer Sue Vertue. She’s also Moffat’s wife.

Here’s the image in context (sort of; the theme music has been overlaid):

What’s notable in the video is that we can tell that it’s clearly an object. If it was a “lighting thing,” it would disappear or change as the camera moved.

What do you think? Is it just a weird optical illusion? A piece of production equipment that accidentally got in shot? Or a deliberate in-joke?

(Can you imagine the Doctor meeting Sherock? They’d hate each other, and always be trying to outsmart and outsuperior each other.)

Thanks to Neima for the Combom link. H/t @TheDailyEmma for the video.

(If you stumble across a cool Doctor Who thing, feel free to email me with a link.)