Doctor Who: The Best Episodes From Each Modern Series

During the watchalong/tweetalong of Gridlock, (God bless Emily Cook for organising those during lockdown), Russell T Davies tweeted:

"Truth is, I like pushing that character. I don't have much time for character descriptions like 'never cruel or cowardly.' Sorry. But never limit your lead."

Well, the Doctor becomes dangerously limitless near the end of this particular life. We all know and love David Tennant's popular incarnation for his infectious, cheeky chappy charisma, and slim and a little bit foxy look. But there's always been an undercurrent of self-aggrandising - yep, much like his previous and later versions. Ancient North Martian? Linguistic showoff!

He sees that limitless ambition in Captain Adelaide Brooke and her descendants. But this goes from wide-eyed wonderment to wild-eyed wanderlust: screwing the Laws of Time to save someone as "important" as Adelaide. Undaunted in the face of the Doctor's vainglorious omnipotence, Adelaide - in a bravura turn by Lindsay Duncan - blindsides the Time Lord Victorious in the most devastating way.

Conversely, it would've been an equally dramatic denouement had the Doctor activated Action Five - a la pushing the lever in The Fires of Pompeii. Imagine it: the Doctor, instead, having to stop Adelaide from escaping her fixed point fate, catalysed by Steffi Ehrlich's heartbreaking final moments of watching a message from her little girls, then devastatingly transformed by the infected water.

The water zombie monsters are effectively terrifying with their Halloween contact lenses, and remarkable running speed when almost catching up to the Doctor and Adelaide despite them rocketing away on good old Gadget. Their ear-piercing scream is akin to the bone-chilling Aztec death whistle. And to think, their scary features were toned down following the rushes.