"And if you go chasing robots..."

The TARDIS has been taken out of time and space altogether. It sits in a white void, one seemingly unpopulated except for by silent, insistent White Robots. Pressed by Zoe (Wendy Padbury) as to where they’ve ended up, Patrick Troughton’s Doctor Who notes, not without fear, “We’re nowhere. It's as simple as that.”

Those White Robots were a recycled monster, costumes constructed for an episode of the BBC SF anthology Out of the Unknown (1965-71). It was called The Prophet, and was adapted from Isaac Asimov’s short story Reason. In both, the experimental robot QT1, designed for working on an orbiting satellite, questions how mere humans could have created itself and its brethren. It concludes that they could not have. That machines must have been made by other machines. QT1 then decides that the station’s power generator is God, and quickly becomes hailed as its, well, check the episode’s well-it’s-catchier-than-the-story’s title. The Prophet was shown on 1st January 1967 on BBC Two, and then repeated on 27th May of the same year on BBC One.

In Spring 1968 the Doctor Who production office found itself in crisis. Crises, often self-created ones, weren’t uncommon under producer Peter Bryant, but this crisis had multiple repercussions, just one of which we’re going to deal with here. The Dominators, written by regular Doctor Who writers Mervyn Haisman and Henry Lincoln, had been cut from six episodes to five late in the day. This not only incurred the authors’ wrath, it left the series an episode short.

To fix this, Bryant and his script editor Derrick Sherwin decided to add an episode onto the front of the final serial of the current production “season”, The Mind Robber. This four part story was being written by Crossroads co-creator Peter Ling. It was inspired by Ling’s observations his soap opera’s audience, who would send letters, and even birthday and Christmas cards to the set. But they were addressed to the characters rather than the actors who played them. More, when the cast of Crossroads encountered the series’ fans in the street they would, they reported, often talked to as though they were the characters, being commiserated on onscreen tragedies and passed information the viewers knew but their characters did not.