Part One is a pretty solid set up for the episode. Ainley and O'Mara bounce off each other brilliantly in it, and the intriguing time period and location, Stevenson's Rocket, was very cool.

But it descends into nonsense quite quickly in the second part. So much so who even knows what's happening by the end. 6 and Peri are just so poor in this season, it's unfair on Bryant and Baker.

The Doctor needs to meet more Time Lords, cos…