BBC

Doctor Who fans knew what they were expecting heading into Fugitive Of The Judoon. The titular anthropomorphic rhino police force would lose another alien prisoner and their search for it would endanger a load of regular humans. So far, so third season premiere, we thought, and we couldn't have been further from the truth.

The return of Captain Jack Harkness brought some cheesy comic relief, foreshadowed a future storyline and, more importantly, removed the Doctor's companions from her. Alone on Earth, the Doctor looked into the mystery behind a woman (Jo Martin) who was later revealed to be a Time Lord, hiding as a human with the use of chameleon arch technology.

Which Time Lord? Well, as the Doctor dug up a version of her own TARDIS buried in a particularly deep grave, it seemed she'd found a future version of herself. Except, this version had no memory of her at all, just as she had no memory of this incarnation in her own past. Eventually figuring out that this was a version of her from some time before the Time War and the more recent destruction of Gallifrey, the Doctor was left with the same puzzle that the fans had.

Why didn't she remember ever having been this woman? How could this person possibly fit into her past? The obvious answer seemed that this is an impersonator of some sort, perhaps even the Timeless Child herself, but show-runner Chris Chibnall came out and denied that rumour.

With him stating that this is definitely the Doctor, and that there is no trick or alternate universe explanation, the answer must lie somewhere in the rules of regeneration.