Doctor Who Series 10: 6 Theories On Who's In The Vault

OK, so they probably aren't going to reveal that the Doctor isn't really the Doctor, as that would be a massive slap in the face to the fans. That doesn't mean it definitely isn't a version of the Doctor in the vault, though. What if it contains his next regeneration?

Combining Steven Moffat's love for the timey-wimey and the common knowledge that Peter Capaldi is leaving at the end of this year, it is suspected that the Doctor's regeneration will be teased and played with throughout the series. So what if the next Doctor is already hiding in plain sight?

This wouldn't even be the first time the Doctor's next regeneration has echoed back through time. Back in the Fourth Doctor's final story Logopolis - which Moffat is known to be a big fan of - the Doctor encounters a mysterious figure known as the Watcher, who is later revealed to be a kind of ghost that foreshadows his imminent death.

We have no idea how this would logistically work, either within the show or out of it - why is the next Doctor in the vault in the first place? Would Moffat incorporate the next Doctor into his storyline when that character will be the creation of incoming showrunner Chris Chibnall? - but it's still a theory worth considering.