Should you visit Roald Dahl Plass on Google Maps, you will notice a jovial waving woman. She resembles a nanny who adheres to the philosophy that a small heap of sweetener allows medication to travel effortlessly down the gullet in a manner that most satisfactory. This appearance has not been lost to Tumblr user FireFlyAstoria, who has hypothesized a most supergallifreysticexpialidocious theory:

Do you know who that is? Yep, that's Mary Poppins.

Do you know where that is? Yep, that's Cardiff. Specifically, that's outside the Roald Dahl Plass.

Do you know what the Roald Dahl Plass is? Yep, the roof of Torchwood.

Do you know why Torchwood is there? Yep, that's because of the rift in Cardiff, specifically that rift for a specific reason.

Do you know where the Doctor re-fuels the TARDIS?

So tumblr was right.

Mary Poppins IS the Doctor.