The First Incarnation of the Doctor would have been considered an adolescent by Time Lord standards, according to his grand-daughter Susan. And yet he was about 450 years old when he regenerated for the first time. He may have looked like the oldest of the Doctor's incarnations, but in "reality" he was the youngest. (Conversely, the Eleventh Incarnation may look the youngest, but he's actually the oldest.)
So for 450 years, the Doctor always looked like the actor who portrayed him, William Hartnell. (However, I still think that James Buckley could play the First Incarnation as the Doctor in the fifty years he spent as a teenager.)
Therefore, if fanficcers want to show pictures of the "First Doctor" as a younger Time Lord, then they should track down pictures of Hartnell from earlier in his career and even personal pictures if you wanted to show him in his youth. (Although I don't think those are available....?)
Save for one of these pictures, they're all from Hartnell's film career. I think anything else he did on television should be locked in place as being about that particular character only as seen in Earth Prime-Time. (The same goes for any actor when dealing with these fanfic inspirations.)
|Arguing a point of academia with a Time Lady classmate?|
As a teacher at the Time Lords' Academy?
The Eleventh Incarnation wasn't the first to rock the bow tie!
Perhaps the uniform was required in the Prydonian Chapter?
Well, he must have worn jammies in the TARDIS at some point!