The 254th episode of Doctor Who airs on the BBC, the first of the series’ seventh season. Nicholas Courtney returns as the Brigadier, now a series regular, while Caroline John makes her first appearance as the Doctor’s companion, Liz Shaw. As of this story, the Doctor is exiled on Earth indefinitely by the Time Lords, unable to travel in space or time in the TARDIS.
This is Jon Pertwee’s first episode as the Doctor, and the first Doctor Who episode filmed in color. Due to a BBC studio strike, the story is filmed entirely on location, a rarity for Doctor Who.