Doctor Who

In Mawdryn Undead , to cite one example, the Doctor states that he has 8 regenerations left, making him (Peter Davison) the 5th incarnation.

David

Doctor Who has always contradicted itself.

In a Tom Baker/4th Dr story ( The Brain of Morbius , I think), there is a suggestion that there were pre-William Hartnell incarnations of the Doctor, but all other references would disagree with this concept, so Morbius is probably best ignored.

Other examples:

In The Five Doctors , the 1st Dr (Richard Hurndall filling in for the deceased William Hartnell) tells Tegan and Turlough that he is the "original" Doctor.

In the same story, the 1st Dr asks the 5th Dr (Peter Davison) which regeneration he is. The 5th Dr replies "fourth" (4th regeneration = 5th incarnation ).

In Time and the Rani , Sylvester McCoy's Dr specifically refers to himself as being the 7th.

Etc etc etc.

Im no expert and have only seen 'bits' of the old series but arn't I right in thinking that the 're-generation' thing only came about when William Hartnell quit?

Indeed.

The concept was not dreamt up until Hartnell wanted to leave.

"Regeneration" is not a Dr Who invented word of course, it is in the dictionary, and similies include "rejuvantation", "re-incarnation" and "rebirth".

The concept that the Time Lords specifically favour the word "regeneration" above any similies was not apparent until some point during the Tom Baker (4th Dr) era.

In fact, the word "regeneration" was first used for the Jon Pertwee - Tom Baker (3rd Dr - 4th Dr) crossover. The first two regenerations were described in the actual episodes with much more basic words (i.e. "change").

Do you mean synonyms rather than "similies" (sic)? A simile is a phrase in which two dissimilar items are likened to each other e.g. 'as easy as pie'. A synonym is a word that has a similar meaning to another. I'm not nitpicking or criticising for the sake of it - just trying to be helpful.