K-9 and Company was a projected spin-off series of Doctor Who, featuring former series regulars Sarah Jane Smith, an investigative journalist, and K-9, a robot in the shape of a dog. Both characters had been companions/assistants of the fourth Doctor, played by Tom Baker, and were considered two of the most popular companions among the show's fans.
The pilot episode, "A Girl's Best Friend", was broadcast on the 28 December 1981. As in Doctor Who, John Leeson provided the voice of K-9 and Elisabeth Sladen played Sarah Jane Smith. Sarah Jane gained a companion/assistant of her own, her aunt's ward Brendan Richards, played by Ian Sears.
The pilot episode began with Sarah discovering a boxed-up K-9 Mark III, a gift from the Doctor. The plot which followed involved a strange mixture of occult spookery and mundanity. Robed pagans chanting "Hecate!" seem straight off of an Earth-set episode of Doctor Who, but the supposed goddess revealed as a human in a mask does not. The action took place in early to mid-December, the last scene taking part on Christmas Day.
Many Doctor Who fans remember it most clearly for the theme music, composed by longtime fan Ian Levine, which might be politely described as "interesting".
The viewing figures for the pilot were very strong, but due to a changeover of management at the BBC it did not go to series (the new bosses disliking the idea while the previous regime had approved it). It remains a curiosity, the sole direct televisual spin-off of Doctor Who.
Despite the non-continuation of the series, it was acknowledged within Doctor Who itself as part of the show's reality: in the 1983 anniversary special, which featured appearances by many past companions, Sarah Jane makes her entrance accompanied by K-9 Mark III.