Though every episode of the series to date has been flagged for indefinite retention due to its popularity in foreign markets, for the first time, the BBC archive issues instructions to erase most of the first three seasons of Doctor Who. This covers every episode from An Unearthly Child through the final episode of The Gunfighters, and it is at this point that many complete stories are lost forever in video form (such as Marco Polo and The Massacre), and huge swaths of the series’ run are erased as well (much of the 12-part epic The Daleks’ Master Plan). The series thus far has been produced in 405 line PAL videotape, and a new 625 line standard will become the default recording/transmission option in 1968. Many of the erased episodes are recovered years later from the foreign markets to which they were sold, from Africa to the Middle East, but many are never seen again.
