The BBC is, today, very good at archiving programming material. All output is kept for at least five years, and the overwhelming majority is kept permanently (e

The BBC is, today, very good at archiving programming material. All output is kept for at least five years, and the overwhelming majority is kept permanently (exceptions are things like long-running quiz shows, where samples of material are kept post five years, although any disposed material is offered to the BFI and other third parties before being junked). Doctor Who wasn't scrapped in the name of saving space, it was scrapped because nobody thought it was worth keeping. The shows couldn't be repeated (because at the time, Equity had negotiated limits on repeat rights), and quad tape was very expensive and easily re-used. More importantly, nobody really thought that Quad was an appropriate archiving format. Programs would be tele-recorded onto 16mm for overseas sale and archive. This is not, in of itself, a crazy idea - try finding a quad tape player today vs a 16mm projector. The problem at the time was there was no mandate for archival, so the engineering department were junking the tapes, and the commercial department (who were selling Doctor Who on to other broadcasters) weren't retaining the 16mm reels. Even in the 1970s, many people were still not convinced of the value of archiving TV output. It's not totally dissimilar to the early days of the web - it was seen as ephemeral. This was happening at pretty much every broadcaster around the world - Wikipedia has a pretty big list of lost TV programs, most of which were wiped for space.