Re: 7X13 The Name Of The Doctor(Grading/Discussion)(SPOILERS!)
Well, the only thing we can be sure of is that he's NOT an incarnation who's somehow been blocked from the Doctor's memory: the current Doctor knows full well who he is, knows what he did, and thinks that he, unlike himself and the 10 previous incarnations we already knew about, doesn't deserve the name 'Doctor'.
"Some days are better than others. They say that where I come from."
"Loudly, I imagine, on the day you left."
(Blake's 7 - Rumours of Death)