The BBC is no stranger to wiping and/or losing their programs. Up until the late 70s, they would wipe the master tapes of their own shows to record new material on, a cost saving measure that continued to be used in the 90s despite it commonly being stopped two decades earlier. Prolific shows missing large chunks of their episodes include comedy series such as Dad's Army and Not Only But Also, one off specials such as The Mad House on Castle Street (in which Bob Dylan made his first acting appearence) and perhaps the most prolific example of this, 97 episodes of the classic Sci-Fi series Doctor Who. Oddly enough, many writers on Doctor Who (such as Gerry Davis and Bryan Hayles) and even a couple of directors (Innes Lloyd and Derek Martinus) worked on a BBC soap opera called United! alongside their work on Doctor Who, and United! is missing far more than Doctor Who ever did.
The premise for United! was fairly unconventional for a typical soap opera-it followed the life and times of Brentwich United, a fictional second division football team (that's soccer for the Americans reading this). The series made use of a nearby football field on the grounds of Stokes City in order to achieve as much authenticity for the series as possible. This backfired somewhat when a real life football team, the Wolvenhampton Wanderers, filed complaints that the series was based on their team.
This was the least of United!'s problems however, as it was considered too soft for the male demographic despite the football angle, and too male-oriented for the female demographic because of the football angle. As such, United! was cancelled after two seasons. Despite only running for two years, United! managed to produce 147 episodes in the two years it was on air, admittably a pitiful amount compared to most soap operas, but still a sizeable amount of episodes. However, The BBC decided to wipe the master tapes for all episodes of the series, presumeably around the same time they started wiping Doctor Who episodes, or perhaps a bit earlier.
Today, despite a constant effort to find other lost media The BBC has wiped over the years, no episodes for United! have been discovered and the entire 147 episode series is missing. This could perhaps to be attributed to the fact that The BBC seems to have not distributed any of the series to any other country like it did with other shows that have been found over the years (we know that one episode of Doctor Who, episode 7 of The Dalek's Master Plan aka 'The Feast of Steven' was lost forever in a similar fashion), though if this were the case, it is unlikely we will ever see any of United! again.