Doctor Who: EVERY Steven Moffat Episode Ranked Worst To Best

Quite why Moffat only co-wrote one half of a two-part story is anyone's guess, yet here we are with The Zygon Invasion & The Zygon Inversion... three quarters of which was written by Peter Harness.

Inversion is the better of the two episodes though that's mostly down to Peter Capaldi, who acts his socks off with a poignant and sadly ever-relevant speech about the futility of war. It's delivered with unparalleled intensity and integrity by Capaldi, and stands as one of his finest moments as the Doctor.

And credit to the writers too – the commentary on warfare and the pointlessness of weapons in procuring peace is expertly woven into the story in the form of the Osgood boxes, and leaves you with a lot more to chew on than your average Doctor Who episode.