Ol' Peculier wrote:
Of coruse, the whole regeneration thing relied on the William Hartnell Doctor being the first, which AFAIK was never implied or denied.
In the Five Doctors, 5 clearly identifies himself as the fourth regeneration, and 1 comments on there being 5 of him. I don't know if it was made clear before then.
As I mentioned over on IMDB, where there is practically a war about this, the regenerationlimit was never supposed to limit the Doctor, it was supposed to limit the Master, and it didn't even do that, as he is on, at least, his 16th or 17th body by now. It was never supposed to have any influence on the Doctor, as his 13 regeneration was still decades into the future and what is the odds that a silly little sci-fi show goes for that long?
Canon is changed all the time, when needed. I mean, I think that we are all in agreement that the Doctor is not half-human on his mothers side. In fact, I might be tempted to compare Who to the bible, in that it is information created by dozens of people over many years, and not a lot of it squares up completely with all the other information.