Season 6B

Season 6B or Season 6 (b) is a revision and expansion to televised Doctor Who canon which places new adventures for the Second Doctor between The War Games and the first appearance of the Third Doctor at the start of Spearhead from Space.

The theory
To account to continuity discrepancies, Paul Cornell proposed the theory in The Discontinuity Guide which he wrote with Martin Day and Keith Topping.

The theory could explain the following continuity problems:


 * How the Third Doctor had several items not possessed by him before his trial (Spearhead from Space)
 * How the Second Doctor knows that the Time Lords would remove certain memories form Jamie and Zoe. The Doctor disbelives llusions of Jamie and Zoe because he knows that the Time Lords wiped their memories of all but their first adventures with the Doctor. Therefore Jamie should not have recognised Brigadier Lethbridge-Stewart. But from the Doctor's point of view, this should not have happened yet (The Five Doctors)
 * Why Second Doctor and Jamie appear noticeably older in their guest appearances (The Five Doctors and The Two Doctors)
 * Why Jamie McCrimmon can know about the Time Lords (The Two Doctors)
 * How the Second Doctor could work for the Time Lords (The Two Doctors)

The theory goes that the Second Doctor worked for the Celestial Intervention Agency. During this time, the Second Doctor apparently regains Jamie and Victoria Waterfield, acquires a Stattenheim remote control device to summon his TARDIS, and undertakes the mission which was related in The Two Doctors. Eventually, either the Time Lords tire of keeping the Doctor on a leash, or the Doctor rebels and attempts to escape once more. This results in the exile which begins in Spearhead from Space.

To explain why the Sixth Doctor does not remember his own past in The Two Doctors, it is also suggested that the Time Lords wiped the Second Doctor's memory of the events of Season 6B (the Third Doctor did claim significant memory loss in Spearhead)

The feasibility of Season 6B is helped by the fact that at the end of The War Games, the Doctor is not shown physically changing appearance, unlike most other regenerations save the Eighth Doctor to the Ninth. Nor is any change depicted at the start of Spearhead from Space.

The Three Doctors
The Second Dcotor is called on by the Time Lords to help the Third Doctor. But the fact that gives this away is that the Doctor is alone so it could be placed before The War Games but if this is so then when the Third Doctor makes contact with the Second, then the Second should know about his trial, his exile and regeneration(otherwise, this would prove that Time Lords have the power to send messages very carefully and not mention any events if the above is true). If this takes place after it, then this contradicts the aftermath of The War Games, as he is seen regenerating but otherwise, these events could have been prevented by the CIA.

The Five Doctors
As noted above, the Second Doctor claims that Jamie McCrimmon and Zoe Heriot should not recognise the Brigadier, as they had their memories wiped. Some evidence in dialogue confirm that this story happens after The Three Doctors. Since the Second Doctor would not be aware of the memory wipe if he was taken before The War Games, there is no easy way that he can know this, and still be the Second Doctor.1

The Two Doctors
The Two Doctors shows an aged Second Doctor traveling with Jamie on a mission for the Time Lords. However, Jamie was not aware of the Time Lords until The War Games (This was confirmed as an error by the The Two Doctor's writer, Robert Holmes.) The aged appearance of the two actors also suggests it is after The War Games. The later Time Crash, however, attempted to rationalize the age differential issue but in fact does not as we see the Second Doctor and Jamie prior to meeting the Sixth Doctor and they are still aged.

Novels

 * Players (a Sixth Doctor novel featuring a flashback to the Season 6B period]
 * World Game (set just before the Second Doctor's part of The Two Doctors from the point of view of the Second Doctor)

Short stories

 * Mother's Little Helper
 * Scientific Adviser
 * Reunion

Audiobook

 * Helicon Prime (with Jamie)

Other information
The idea of a post-The War Games Second Doctor, as Cornell acknowledges, had already been introduced in the TV Comic comics story, Action in Exile sees the Doctor arrive in London without his TARDIS, and he checks into the luxurious Carlton Grange Hotel. From this base, he proceeds to have five Earth-bound adventures, culminating in The Night Walkers. In this story, the Doctor investigates tales of scarecrows walking. He discovers that the scarecrows have been animated by the Time Lords to capture him, and we learn that the Doctor escaped from the Time Lords before they could complete his sentence of a forced change of appearance. The scarecrows take him into the TARDIS and proceed to trigger his regeneration, leading directly into Spearhead from Space. (The scarecrows get a brief mention in the Doctor Who Unbound audio play, Exile and a variation is featured in the televised episodes Human Nature and The Family of Blood -- both episodes were written by Cornell.)