When Doctor Who fans refer to “lost stories”, they mean one of two things. Usually, they're talking about the episodes which were purged from the BBC Archives during the 1970s, and for which only the soundtrack now exists.

But sometimes, they mean the stories that -- for one reason or another -- never even made it into the recording studio. Some of these were just one-off submissions that were quickly dismissed by the Doctor Who production office of the time. Others enjoyed considerable development until they were finally derailed at the last minute.

It is, of course, difficult to discuss these “unmade stories” in great detail, because often very little documentation remains (or even existed in the first place), especially for those ideas which were immediately discarded. However, we'll use a simple colour code to give you some idea of just how far advanced each proposal was before it finally ended up on the Doctor Who scrap heap:

• Stories with a red banner are those which were never seriously considered by the production office. These probably never made it past the initial pitch, let alone a more detailed storyline. They never appeared on a tentative season schedule. No guest cast or production personnel would have been assigned to these stories.
• Stories with a blue banner were more seriously developed. They almost certainly made it to the storyline stage, and some scripting may have even taken place. They may have appeared on a season schedule and even had a director assigned, but it is unlikely that any casting would have even been considered.
• Stories with a green banner were those which the production office had every intention of making, but which ultimately -- for a variety of reasons -- they never did. These stories probably had partial or even full scripts written, and likely appeared on a season schedule. They may well have had a director assigned, and some potential casting may even have taken place.

Obviously, these three categories are somewhat subjective, but bear in mind that they are merely intended to serve as general guidelines to put these “lost” stories in some perspective. Also, note that stories about which nothing is known -- beyond the name of an author -- will usually not even merit an entry.