Almost forty years later, though, the cast of the story have been reunited and chief among them is Tom Baker, the Fourth Doctor himself who played the role from 1974-1981.
Baker has previously donned his iconic coat and scarf for a charity appearance, with this new episode being the first time he portrayed the character in the official series since his run that lasted from 1976 to 1981. First off, he turned up in non-canon multi-Doctor special "Dimensions in Time", which aired as part of the 1993 Children in Need celebrations.
This is technically the third time Baker has returned to Doctor Who since regenerating into Peter Davison.
He also appears in the flesh, in new, live-action footage of the Doctor as an old man.
The story sees the Doctor with Romana, his companion played by Lalla Ward, working with a retired Time Lord to defeat Skagra, an inmate of the prison planet Shada, who seeks to discover secret information about the prison world.
Filmed at the BBC Television Centre earlier this year on the set of the original Tardis from 1979, it combines...
Describing his return to the role, the 83-year-old actor said the Doctor "probably never left me". A digital download hit the Web on Friday, available from iTunes and other outlets. However, filming for the episode, which was supposed to be the end of the 17th series of Doctor Who, came to a halt. Unfortunately, strikes wracked Britain for months and the episode was put on the backburner, with some of the existing footage later used in the Doctor Who 20th anniversary special.
"'Shada" was one of my favorite "Doctor Who' stories".
The BBC finally completed the story-with new effects, a score, and linking narration by Baker-and six shortened episodes were given a 111-minute VHS release in 1992.
The lost episode will be available to buy on digital download and will be released on DVD and Blu-ray on December 4.