Chronology, Continuity & Canon are the eternal obsessions of fans of all TV shows, not just fans of Doctor Who. At its simplest, when something is established we don't like it when it's subsequently contradicted. We like to know the exact order when things happen and we pay attention when characters mention things we haven't seen on TV. It has always been part of the fictional reality of Doctor Who that the characters have a life beyond what we see them doing on TV. The inference is that the adventures we see the Doctor having on TV aren't the only ones he has. Question is, what are those adventures and when do they take place? And before you know it, you're off and playing Hunt The Story Gap, trying to track down the places where those non-TV adventures happened. Cue that other eternal hallmark of the fan - The List.

For the TV stories, it's usually the case that Production Order and Transmission Order are the same, so the order you see them in on telly is pretty much the order they happened to the Doctor, though there have been exceptions over the years. In this timeline there are two clear instances where the production team swapped stories for reasons of contrast that clearly should not have been swapped around so I've corrected those here. With the Big Finish audios, arguably Canon since The Night Of The Doctor, it's not always so easy to know where a particular story takes place. I call it Minding The Gaps. In general I adhere to the primacy principle, so if Story A is released before Story B, and they both go in the same Story Gap, then Story A goes in first unless there is clear evidence to the contrary.

The Big Finish audios have to take place in the Story Gaps between television adventures, which are the Primary Texts of Doctor Who. Audio adventures, original novels and comic strips are all Secondary Texts. So, when it comes to continuity, the general principle is that the Primary Text takes precedence unless there's a compelling reason not to adhere to it - The Primacy Principle. If it's clear that there is a run of consecutive adventures taking place then the same rules apply as on Television: if A is released before B, then A takes place before B, unless there is a compelling reason for it not to. I call this the rule of Chronological Sequentialism.

So in drawing up this chronology, I've only gone by what I've actually heard when listening to the audio when working out where a particular story appears in the Doctor's timeline. Just because a CD release for a particular story says it takes place between two stories that doesn't mean I'll agree with it - I'll listen and come to my own conclusions based only on what I've heard. Of course, some placements are inevitably arbitrary as there is no clear guide as to where they go. In those cases I've just picked a spot where it seems to me that it might fit and isn't too similar to the stories around it.

I've also corrected two infamous continuity errors concerning The Curse of Fenric & Ghost Light and Silver Nemesis & The Greatest Show In The Galaxy caused by the production team swapping them in the running order for transmission. That was a simple fix compared to sorting out Seven's Timeline.

On television, the Seventh Doctor's timeline is straightforward: Mel, Ace, Alone, Regeneration. But in univers of Television Plus Big Finish, things are a lot more complicated...

Seven starts off travelling with Mel, meets Ace, who replaces Mel and stays with him until the end of the TV Show in 1989. Virgin Books' The New Adventures were the first to carry on where the TV Show left off, a timeline that takes place in The Books Universe. But then Big Finish go and complicate things by adapting those books as audio adventures. This means a version of that Virgin Books Timeline occurs in the Big Finish Universe. So how do you reconcile the various arrivals and multiple departures? The answer, as ever, is Chronological Sequentialism, such that what is released first goes first unless there is clear evidence to the contrary.

The first addition to Seven's initial timeline was Hex, giving us the following companion order:

Mel. Ace. Ace & Hex. Ace Again. Seven Alone. Regeneration.

But Big Finish then adapted the New Adventures, featuring both Bernice Summerfield and Chris & Roz. The simplest way to accommodate those audios was to put them after Ace & Hex, since that companion combo had previously been established. That gives us:

Mel. Ace. Ace & Hex. Ace Again. The New Adventures. Seven Alone. Regeneration.

The next question was what to do about Raine Creevy, who was intended as Ace's replacement in the unmade Season 27. Big Finish alter the original intention by not having Ace leave, but since the Lost Stories featuring Raine were intended to take place after Survival they should really go there, before the earliest "proper" Big Finish Adventures. Adding the Raine audios to the timeline gives us this:

Mel. Ace #1. Ace & Raine. Ace #2. Ace & Hex. Ace #3. The New Adventures. Seven Alone. Regeneration.

Next we have the further complication of the return of Raine Creevy and Elizabeth Klein.In UNIT: Dominion Seven tells Raine about Klein, putting the initial trilogy of adventures with her earlier in his timeline, something that Klein expecting "the umbrella man" would seem to confirm. But then there's also the question of The New Adventures of Bernice Summerfield to consider as that reunites Seven with both Benny & Ace, fighting first the Daleks, then Sutekh. So where do these audios fit into the gap between the end of the New Adventures timeline and the Doctor's regeneration?

The answer lies with UNIT: Dominion. That story has Seven telling Raine about Klein, meaning the first Klein Trilogy has takes place before it. Come the second Klein Trilogy, Klein asks where Raine is, meaning that trilogy takes place after it. Applying the rule of Chronological Sequentialism means that Seven being reunited with Benny happens after the second Klein trilogy. Add in Ace & the Doctor being reunited with Mel, which really has to go after Ace & Hex, and you get a final version of Seven's timeline that, barring any further changes, looks like this:

Mel. Ace #1. Ace & Raine. Ace #2. Ace & Hex. Ace #3. Ace & Mel. The New Adventures. Seven Alone #1. Klein Trilogy #1. Raine. UNIT: Dominion. Seven Solo #2. Klein Trilogy #2. Seven Solo #3. New Benny & Ace. Seven Solo #4. Regeneration.