10 MORE Unanswered Mysteries From Doctor Who

The twelfth season finale of the Doctor Who revival fairly chucked a spanner into the works for Whovian historians. Those who had diligently been trying to keep track of the Doctor's timelines threw their hands up in the air in frustration, now with the knowledge that William Hartnell's kidnap of Ian Chesterton and Barbara Wright was no longer the earliest adventure.

Just how old is the Doctor? The Eleventh Doctor reckoned himself at around 2,000 years, though the Twelfth Doctor technically lived another five billion years, though it is unsure if this is counted as the confessional dial was locked in a single day. The First Doctor thought himself to be around six hundred years old, which left more than a millennium to go through the rest of these regenerations.

However, now it is revealed that all of Time Lord society derives from the abilities of the Timeless Child, or the Doctor herself, as it was she who brought the gift of regeneration to Gallifrey. Does this mean she is older than the rest of her species? Rassilon spits that they are responsible for a billion years of Time Lord history, so is the Doctor even older again than this? And how many regenerations is she on now?